UMASS/AMHERST 


31E0bt>DD5fiS5Dfi7 


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http://www.archive.org/details/soilinvestigatioOOwhit 


i:ja3i:iA.'Bir  of  tii^ 

Massaclnasetts  ' 

OCT  22 1910 

^gric^iltural 
College 


SOIU      INVESTIGAXIOrsl3. 

MILTON    WHITN-EY. 

(^Extracted  from   the   Fourth   Annual   Jleport,) 

Maryland    Ageicultueal    Experiment    Station. 


EEPOET   OF   THE   PHYSICIST. 


By  Prof.  Milton  Whitney. 


SOIL    INVESTIGATIONS. 


Introduction. 


It  is  proposed  at  this  time  to  give  a  brief  account  of  the  soil 
investigations  carried  on  by  the  Station  and  attempt  to  point  out 
the  application  of  the  results  and  conclusions  to  the  explanation  and 
solution  of  problems  in  practical  agriculture. 

We  are  glad  to  report  that  the  U.  S.  Government  has  taken  up 
this  work,  and,  through  the  Weather  Bureau  of  the  Department  of 
Agriculture,  has  placed  a  sum  of  money  at  our  disposal  to  enable  us 
to  complete  some  work  on  hand  in  order  to  prepare  a  full  report  or 
monograph,  to  be  ready  for  publicaLtioli'"  *by'  liext  July.  In  view  of 
the  fact  that  the  report  to  be  issued  by  the  Government  will  of  neces- 
sity be  much  fuller  and  more  exhaustive  than  this  can  be.  and  will  con- 
tain a  detailed  description  of  the  methods,  formulae  and  data  upon 
which  our  lines  of  reasoning  are  based,  we  will  introduce  into  this 
report  only  such  statistical  and  other  data  as  will  make  the  narrative 
complete — referring  all  who  wish  to  follow  the  subject  more  closely 
and  in  further  detail  to  the  Government  report. 

It  has  taken  six  years  of  constant  application,  observation  and 
study,  in  the  Held,  plant  house  and  laboratory,  to  gain  a  clear  idea 
of  the  nature  and  structure  of  the  soil  in  its  relation  to  meteorology 
and  agriculture.  When,  in  the  fall  of  1890,  the  work  was  com- 
menced here  in  its  application  to  the  soils  of  Maryland,  several  fun- 
damental principles  of  soil  physics  still  remained  to  be  worked  out. 
This  required  the  use  of  very  expensive  apparatus,  only  to  be  found 
in  a  well-equipped  physical  laboratory.  It  was  essential,  also,  that 
the  work  be  based  upon  the  most  thorough  geological  data  to  show 
the  area  and  distribution  of  the  different  soil  formations.  There  wa& 
no  reliable  geological  map  of  the  State,  and  the  Director  of  the  U.  S. 
Geological  Survey  stated  that  the  Professors  of  Geology  of  the  Johns 
Hopkins  University  had  all  the  available  data,    and  were   themselves 


250  MARYLAND    AGRICULTURAL 

working  out  in  more  detail  tlie  geology  of  Maryland,  and  advised  a 
co-operation  with  thein  in  this  soil  work. 

The  work  of  this  division  of  the  Experiment  Station  on  tlie  inves- 
tigation of  soils  was,  therefore,  located  at  the  Johns  Hopkins  Uni- 
versity. By  permission  of  the  Trustees  of  the  University  the  work 
was  moved  in  June  to  their  large  estate  of  Clifton,  on  the  Harford 
Road,  where  it  is  at  present  being  carried  on.  The  reasons  for  this 
and  our  relations  with  the  University  are  more  fully  set  forth  in  tlie 
Director's  report. 

The  President  of  the  University  and  the  Professors  in  the  Depart- 
ments of  Chemistry,  Geology  and  Physics  have  shown,  from  the 
first,  an  interest  in  the  work  and  a  cordial  spirit  of  co-operation,  with 
:a  desire  to  have  us  make  a  practical  application  of  their  work  and 
information. 

Argument. 

It  takes  really  very  little  experience  for  one  to  judge  at  a  glance 
whether  a  soil  is  suited  to  grass  or  wheat  or  to-bacco  or  watermelons, 
and  he  has  but  to  turn  up  a  small  handfuU  of  earth  to  see  if  the  soil 
is  in  o-ood  condition,  as  regards  moisture,  for  the  growing  crops.  And 
yet,  agricultural  chemists  have  worked  over  this  problem  for  years, 
argning  points  from  minute  difierences  in  chemical  composition  of 
the  soils  or  plants,  which  their  most  refined  methods  make  none  too 
sure,  overlooking  the  fact  that  the  farmer  can  tell  from  the  a'piiear- 
ance  whether  a  soil  is  in  "good  heart"  and  what  it  is  best  fitted  to 
grow.  The  farmer  cannot  see  these  minute  differences  in  chemical 
composition.  He  judges  from  the  general  appearance  of  the  land, 
the  physical  structure  of  tlie  soil. 

Those  of  us  who  are  engaged  in  agricultural  investigations,  even  in 
soil  studies,  are  not  as  far  advanced  as  the  farmer  in  our  knowledge 
of  the  soil,  nor  will  we  be  until  we  can  understand  and  explain  these 
visible  signs  upon  which  he  bases  his  judgment.  He  has  kept  up 
with  Qur  work  on  the  chemical  composition  of  soils  and  has  applied  it 
and  made  it  his  own.  But  he  goes  further  than  we  have  gone,  for  he 
can  tell,  as  no  chemical  means  will  enable  us  to  judge,  whether  the 
land  is  in  good  condition,  is  fertile,  has  body  and  will  hold  manures, 
is  strong  or  will  shortly  run  out,  is  dry  and  leachy  or  retentive  of 
moisture.  He  can  tell  what  class  of  plants  it  will  best  produce.  In 
this  lies  the  key  to  all  soil  investigations.     Chemical  analysis  has  its 


EXPERIMENT    STATION.  251 

part  to  plaj,  but  we  have  yet  to  get  the  key  to  the  interpretation  of 
its  results.  And  this  key  is  to  be  found  in  the  study  of  the  physical 
structure  of  the  soil  and  the  physical  relation  to  meteorology  and  to 
plant  growth.  Meteorology  has  not  done,  and  is  not  doing,  its  best 
good  for  agriculture.  While  we  admit  it  is  very  important  to  have 
the  rainfall  data  furnished  by  the  Weather  Bureau,  still,  as  the  rain 
does  not  benefit  the  crops  until  it  enters  the  soil,  it  is  very  essential 
that  the  rainfall  be  studied  below,  as  well  as  above,  the  surface  of  the 
ground. 

Crop  production  is  not  directly  limited  by  the  amount  of  rainfall, 
but  by  the  moisture  in  the  soil.  Six  inches  of  rainfall  a  month  may 
mean  a  good  season,  or,  with  this  same  amount  differently  distributed 
throughout  the  month,  the  crops  may  be  injured  by  excessive  wet  or 
by  prolonged  drought.  Changing  seasons  of  wet  or  dry,  hot  or  cold, 
have  far  more  effect  on  the  crops  than  any  combination    of   manures. 

There  is  a  certain  type  of  land  in  this  State,  in  a  certain  geological 
formation,  which  is  left  out  in  pine  barrens  as  it  is  too  poor  to  put 
under  cultivation  ;  another  type,  in  a  different  geological  formatian,  is 
well  suited  to  melons  and  garden  truck  ;  still  other  types,  to  tobacco, 
wheat  and  grass.  This  is  not  a  rnatter  of  mere  plant  food.  ISo  addi- 
tion of  any  amount  or  any  combination  of  available  plant  food  will 
at  once  enable  a  good  wheat  crop  to  be  produced  on  the  soil  of  the 
pine  barrens,  or  on  the  light  truck  lands.  It  is  a  matter  of  available 
water  rather  than  of  available  plant  food,  and  if  after  some  years  the 
light  land  is  brought  up  to  produce  good  yields  of  wheat,  the  whole 
appearance  and  structure  of  the  soil  will  be  found  to  have  changed, 
and  with  it,  the  relation  of  the  soil  to  the  movement  of  water — to  the 
movement  of  the  rainfall  after  it  enters  the  soil. 

And  so  in  the  deterioration  of  land,  in  the  deterioration  of  our 
tobacco  and  wheat  lands.  It  is  not  due  to  loss  of  plant  food  so  much  as 
to  the  causes  which  change  the  whole  appearance  of  the  soil  to  the 
eye — a  change  of  the  physical  structure  of  the  soil,  a  change  in  the 
relation  of  the  soil  to  the  movement  or  circulation  of  water. 

Our  work,  then,  is  on  the  physical  structure  of  the  soil  and  its  re- 
lation to  the  circulation  of  water — the  movement  of  the  rainfall  after 
it  enters  the  soil,  and  the  physical  effect  of  fertilizers  and  manures 
thereon,  as  related  to  crop  production. 


252  maryland  agricultural 

Summary  of  the  Results. 

This  report  will  treat  lirst  of  tlie  underlying  principles  governing 
the  circulation  of  water  in  the  soil,  then  of  the  different  soil  types 
found  in  the  State,  of  their  structure  and  relation  to  the  circulation 
of  water,  leading  up  to  the  application  of  these  principles  in  a  dis- 
cussion of  the  improvement  of  lands.  A  summary  will  be  given 
here,  outlining  the  body  of  the  report,  so  that  it  may  be  followed 
more  easily. 

I.  The  circulation  of  water  in  the  soil. 

a.  Due  to  gravity  or  the  weight  of  water  acting  with  a  constant 
force  to  pull  the  water  downward,  and  also,  to  surface  tension  or  the 
contracting  power  of  the  free  snrface  of  water,  (water-air  surface,) 
which  tends  to  move  the  water  either  up  or  down  or  in  any  direction, 
according  to  circumstances. 

h.  The  ordinary  manures  and  fertilizing  materials  change  the  sur- 
face tension  or  pulling  power  of  water. 

II.  The  effect  of  fertilizers  on  the  texture  of  the  soil. 

a.  There  is  a  large  amount  of  space  between  the  grains  in  all  soils 
in  which  water  may  be  held.  The  rate  of  movement  of  the  water 
will  depend :  1.  Upon  how  much  space  there  is.  2.  Upon  how 
this  is  divided  up,  i.  e.  upon  how  many  grains  there  are  per  unit 
volume  of  soil.  3.  Upon  the  arrangement  of  the  grains  of  sand  and  clay. 

h.  Flocculation — a  phenomenon  of  great  importance  in  agricul- 
ture— changing  the  arrangement  of  the  grains  and  consequently  the 
texture  of  the  soil. 

III.  The  volume  of  empty  space  in  soils. 

lY.  The  relation  of  geology  to  agriculture. 
Y.  Soil  types. 

a.  Reasons  for  establishing  soil  tj'pes. 

h.  The  very  evident  difference  in  texture  is  the  probable  cause  of 
the  difference  in  relation  to  plant  growth  and  to  local  distribution  of 
crops. 

c.  Soil  types  in  Maryland  and  the  samples  from  which  they  are 
made. 

YI.  Mechanical  analysis  of  the  type  soils. 


EXPERIMENT    STATION.  253 

YII.  Approximate  number  of  grains  per  gram  of  soil. 

YIII.  Approximate  extent  of  surface  area  per  cubic  foot  of  soil. 

IX.  The  circulation  of  water  in  these  type  soils. 

a.  The  relative  rate  of  circulation  of  water  in  soils  short  of  satura- 
tion is  very  different  in  these  type  soils  and  probably  explains  the 
difference  in  relation  to  crop  production. 

h.  The  relative  rate  of  circulation  of  water  in  these  soils  when 
fully  saturated. 

G.  The  influence  of  the  total  volume  of  space. 

d.  The  rate  of  circulation  of  water  is  relatively  faster  in  light 
sandy  lands,  when  far  short  of  saturation,  than  in  heavier  clay  lands, 
but  it  may  be  far  slower  in  these  same  light  lands  when  fully  satu- 
rated, owing  to  the  less  amount  of  space  in  the  soil. 

X.  The  improvement  of  soils. 

a.  In  soils  having  as  much  clay  as  the  type  requires,  the  grains 
of  clay  may  be  rearranged  by  causing  flocculation,  or  the  reverse,  by 
the  use  of  ordinary  fertilizing  materials. 

h.  In  soils  having  less  clay  than  the  type :  1.  The  grains  may 
still  be  rearranged,  or,  2.  organic  matter  may  be  precipitated  from 
solution  within  the  soil,  in  light,  flocculent  masses,  with  lime,  acid 
phosphate,  or  the  proper  mineral  manures,  or  constituent  of  the  soil 
itself,  and  so  fill  up  the  spaces  and  retard  the  rate  of  circulation  of 
the  water. 

I.  The  Circulation  of  Water  in  the  Soil. 

The  motive  power,  which  causes  water  to  move  from  place 
to  place  within  the  soil,  consists  of  two  forces :  gravity,  or  the 
weight  of  the  water  itself,  and  surface  tension.  Gravity  tends 
to  pull  the  water  downward,  and  acts  with  a  constant  force  per 
unit  mass  of  water.  Surface  tension,  or  the  contracting  power 
of  any  exposed  water-surface,  may  move  the  water  in  any  direc- 
tion within  the  soil,  according  to  circumstances.  It  may  act,  there- 
fore, loith  gravity  to  pull  the  water  down,  or  against  gravity  to  pull 
it  up.  This  has  an  important  practical  bearing  on  the  movement  of 
water  in  sandy  lands,  as  we  shall  show  in  speaking  of  the  applica- 
tion of  these  principles  to  our  type  soils. 


254  MARYLAND    AGRICULTUKAL 

The  force  of  gravity  need  not  be  further  considered  here. 

Surface  tension  is  tlie  tendency  which  any  exposed  surface  has 
to  contract  to  the  smallest  possible  area,  consistent  with  the  weight  of 
the  substance.  If  a  mass  of  water  is  divided,  or  cleft  in  two,  leaving 
two  surfaces  exposed  to  the  air,  the  particles  of  water  on  either  sur- 
face, which  were  before  in  the  interior  of  the  mass  and  attracted 
from  all  sides  by  like  particles  of  M^ater,  have  now  water  particles  on 
only  one  side  to  attract  them,  with  only  a  few  air  particles,  compara- 
tively very  far  apart,  on  the  other  side,  where  formerly  was  a  com- 
pact mass  of  water.  All  the  surface  particles  of  water  will  therefore 
be  pulled  from  within  the  mass  of  water,  and  the  surface  will  tend  to 
contract  as  much  as  possible,  leaving  exposed  the  smallest  number  of 
surface  particles,  and  causing  a  continual  strain  or  surface  tension. 
On  any  exposed  water-surface,  there  is  always  this  strain  or  tension, 
ready  to  contract  the  surface,  when  it  may. 

It  is  a  constant,  definite  force  per  foot  of  surface,  for  any  sub- 
stance at  a  given  temperature.  In  the  case  of  liquids  and  solutions, 
in  which  we  are  most  interested,  it  varies  with  the  nature  of  the 
liquid  and  the  substance  in  solution. 

This  is  surface  tension  ;  and  we  have  it  in  the  soil  as  a  strain  or 
tension  along  the  free  surface  of  water  within  the  soil,  which  tends 
to  contract  the  surface  and  so  move  the  water  from  one  place  to  an- 
other as  it  is  needed. 

There  is,  on  the  average,  about  50  per  cent,  by  volume  of  space 
within  the  soil  which  contains  no  solid  matter,  but  only  air  and  water. 
This  we  shall  call  empty  space.  In  a  cubic  foot  of  soil  there  is  about 
half  a  cubic  foot  of  empty  space,  but  this  is  so  divided  up  by  the 
very  large  number  of  soil  grains  that  the  spaces  between  the  grains 
are  extremely  small. 

When  a  soil  is  only  slightly  moist  the  water  clings  to  the  soil 
grains  in  a  thin  film.  It  is  like  a  soap  bubble  with  a  grain  of  sand  or 
clay  inside,"  instead  of  being  filled  with  air.  Where  the  grains  come 
together  the  films  are  united  into  a  continuous  film  of  water  through- 
out the  soil,  having  one  surface  against  the  soil  grains  and  the  other 
exposed  to  the  air  in  the  soil.  As  the  soil  grains  are  surrounded  by 
this  elastic  film,  the  tension  on  the  exposed  surface  of  the  water  will 
support  a  considerable  weight,  for  the  soil  grains,  thus  enveloped,  are 
extremely  small  and  have  many  points  of  contact  around  which  the 
film  is  thicker  and  is  held  with  greater  force. 


EXPERIMENT    STATION.  255 

If  more  water  enters  the  soil  the  film  thickens,  and  there  is  less  ex- 
posed water-surface.  If  the  empty  space  is  completely  filled  with 
water  there  will  be  none  of  this  exposed  water-surface,  and  therefore, 
no  surface  tension.  Gravity  alone  will  act  and  with  its  greatest 
force.  If  the  soil  is  nearly  dry,  there  will  be  a  great  deal  of  this  ex- 
posed water-sarface,  a  great  amount  of  surface  tension,  and  with  so 
little  water  present,  gravity  will  have  its  least  effect. 

The  grains  in  a  cubic  foot  of  soil  have,  on  the  average,  no  less  than 
50,000  square  feet  of  surface  area.  There  is  less,  of  course,  in  a  light 
sandy  soil,  and  more  than  this  in  a  clay  soil.  If  there  is  only  a  very 
small  amount  of  water  in  the  soil  the  film  of  water  around  the  grains 
will  be  very  thin,  and  there  will  be  nearly  as  much  exposed  water- 
surface  as  the  surface  area  of  the  grains  themselves.  If  a  cubic  foot 
of  soil,  thus  slightly  moistened,  and  having  this  large  extent  of  exposed 
water-surface,  be  brought  in  contact  with  a  body  of  soil  fully  saturated 
with  water,  in  which  there  is  none  of  this  water-surface,  the  water- 
surface  in  the  drier  soil  will  contract,  the  film  of  water  around  the 
grains  will  thicken  and  water  will  be  drawn  from  the  wet  into  the 
dry  soil,  whether  it  be  to  move  it  up  or  down,  until,  neglecting 
gravity  or  the  weight  of  water  itself,  there  is  the  same  amount  of 
water  in  the  one  cubic  foot  of  soil  as  in  the  other.  When  equilibrium 
is  established  there  will  be  the  same  extent  of  exposed  water-surface 
in  these  two  bodies  of  soils. 

When  water  is  removed  from  a  soil  by  evaporation  or  by  plants, 
the  area  of  this  exposed  water-surface  is  increased,  and  the  tension 
tends  to  contract  the  surface  and  pull  more  water  to  the  spot. 

When  rain  falls  on  rather  a  dry  soil,  the  area  of  the  exposed  water- 
surface  in  the  soil  is  diminished,  and  the  greater  extent  of  water-sur- 
face below  contracts  and  acts,  with  gravity,  to  pull  the  water  down. 

By  numerous  careful  and  verified  experiments,  we  have  found  that 
fertilizers  change  this  surface  tension  and  modify  the  contracting 
power  of  the  free  surface  of  water  to  a  remarkable  degree,  and  so 
modify  thepower  which  moves  water  from  place  to  place  in  the  soil. 

The  following  table  gives  the  surface  tension  of  a  solution  in  water 
of  several  of  the  ordinary  fertilizing  materials.  This  list  is  not  com- 
plete, and  the  solutions  used  were  of  any  convenient  strength.  The 
results  are  preliminary  to  give  material  for  more  thorough  and  de- 
tailed investigation.     The  surface  tension  is  expressed  in  gram-meters 


256  MARYLAND    AGRICULTURAL 

per  square  meter,  that  is,  on  a  square  meter  (or  yard)  of  liquid  sur- 
face there  is  safiicient  energy  to  raise  so  many  grams  to  the  height  of 
one  meter  (yard.) 

Table  1 : — The  Surface  Tension  of  Various  Solutions. 

{Gram-meters  per  square  meter ^ 
Solution  of  Sp.  ge.  *  Mean.         Highest.      Lowest. 

Salt 1.070  6  T.975  8.126  7.796 

Kainit 1.053  6  7.900  7.993  7.805 

Lime 1.002  4  7.696  7.750  7.674 

Water 1.000  18  7.668  7.923  7.506 

Acid  Phos 1.005  4  7.656  7.800  7.563 

Plaster 1.000  9  7.638  7.730  7.572 

Soil  extract 1.000  5  7.089  7.166  6.969 

Ammonia 0.960  6  6.869  6.950  6.826 

Urine 1.026  10  6.615  6.740  6.471 

*  Number  of  measurements  from  which  the  mean  is  taken. 

"Wullner  gives  the  following  :* 

Sp.  ge.  Tension. 

Water 1.000  7.666 

Sulphuric  acid 1.849  6.333 

"  "    1.522  7.610 

'■  -   1.127  7.556 

Hydrochloric  acid ....  1.153  7.149 

Nftric  acid 1.500  4.275 

" 1.270  6.768 

"   1.117  7.09S 

Salt •       1.200  8.400 

Nitrate  of  potash 1.137  7.276 

*Lehrbuch  der  Experimental  Physik,  Vol.  I.,  p.  341. 


EXPERIMENT    STATION.  257 

The  soil  extract  was  made  by  shaking  up  a  little  soil  with  just 
sufficient  water  to  cover  it;  the  water  was  afterwards  filtered  off  and 
used  for  the  determination.  It  will  be  seen  from  the  table  that  this 
contact  with  the  soil  reduced  the  surface  tension  of  water  very 
considerably.  There  is  little  doubt  that  the  surface  tension  of  soil 
moisture  is  very  low,  much  lower  than  that  of  pure  water.  Salt  and 
kainit,  on  the  other  hand,  increase  the  surface  tension  of  water  very 
considerably  and  raise  it  far  above  that  of  the  soil  extract.  This 
probably  explains  the  fact,  which  has  been  often  commented  on,  that 
an  application  of  salt  or  kainit  tends  to  keep  the  soil  more  moist. 
This  has  often  been  remarked  in  connection  with  the  application  to  a 
clover  sod.  By  increasing  the  surface  tension  of  the  soil  moisture 
they  increase  the  power  the  soil  has  of  drawing  water  up  from  below 
in  a  dry  season. 

Ammonia  and  urine  lowered  the  surface  tension  of  water  con- 
siderably below  that  of  the  soil  extract,  and  far  below  that  of  pure 
water.  This,  probably,  also  explains  a  matter  of  common  observa- 
tion, that  the  injudicious  use  of  excessive  quantities  of  organic  matter 
is  liable  to  "burn  out"  a  soil  in  a  dry  season,  because  by  reducing  the 
surface  tension,  water  can  less  readily  be  drawn  up  from  below. 

This  opens  up  a  field  of  investigation  on  the  determination  of  the 
surface  tension  of  the  moisture  in  various  soils,  and  a  more  extensive 
and  more  systematic  study  of  the  effect  of  various  fertilizing  mate- 
rials on  the  surface  tension  of  water  and  soil  extract,  and  it  opens  up 
a  wide  field  in  its  application  to  practical  agriculture  and  the  use  of 
manures  and  fertilizers. 

This  effect  of  fertilizins;  materials  in  chansfino-  the  surface  tension 
of  a  liquid,  and  thereby  changing  the  force  or  power  which  moves 
water  from  place  to  place  in  the  soil,  is  only  a  first  eiTect,  as  the  con- 
tinued use  of  these  fertilizing  materials  may  change  the  texture  of 
the  soil  itself  and  the  relation  of  tlie  soil  to  the  circulation  of  M'ater. 

II.  The  Effect  of  Fertilizers  on  the  Texture  of  the  Soil. 

Surface  tension  may  be  expressed  in  another  way.  The  2?otential 
of  a  single  water  particle  is  the  force  which  would  be  required  to  pull 
it  away  from  the  surrounding  water  particles  and  remove  it  beyond 
their  sphere  of  attraction.  For  simplicity,  it  may  be  described  as  the 
total  force  of  attraction  between  a  single  particle  and  all  other 
particles  which  surround  it.     With  this  definition  it  will  be  seen  that 


258  MARYLAND    AGKICULTUKAL 

the  potential  of  a  particle  on  an  exposed  surface  of  water  is  only  one- 
half  of  the  potential  in  the  interior  of  the  mass,  as  half  of  the 
particles  which  formerly  surrounded  and  attracted  it  were  removed 
when  the  other  exposed  surface  of  water  was  separated  from  it.  A 
particle  on  an  exposed  surface  of  water,  being  under  a  low  potential, 
will  therefore  tend  to  move  in  towards  the  center  of  the  mass  where 
the  potential,  i.  e.,  the  total  attraction,  is  greater,  and  the  surface  will 
tend  to  contract  so  as  to  leave  the  fewest  possible  number  of  particles 
on  the  surface. 

If  instead  of  air  there  is  a  solid  substance  in  contact  with  the  water 
the  potential  Avill  be  greater  than  on  an  exposed  surface  of  the 
liquid,  for  the  much  greater  number  of  solid  particles  will  have  a 
greater  attraction  for  the  water  particle  than  the  air  particles  had. 
They  may  have  so  great  an  attraction  that  the  liquid  particle  on  this 
surface,  separating  tiie  solid  and  liquid,  may  be  under  greater  poten- 
tial than  prevails  in  the  interior  of  the  liquid  mass.  Then  the  surface 
will  tend  to  expand  as  much  as  possible  for  the  particles  in  the 
interior  of  the  mass  of  liquid  will  try  to  get  out  onto  the  surface. 
This  is  the  reverse  of  surface  tension.  It  is  surface  pressure,  which 
may  exist  on  a  surface  separating  a  solid  and  liquid. 

If  two  small  grains  of  clay,  suspended  in  water,  come  close 
together,  they  rnay  be  attracted  to  each  other  or  not,  according  to  the 
potential  of  the  water  particles  on  the  surface  of  the  clay.  If  the 
potential  of  the  surface  particle  of  water  is  less  than  of  a  particle  in 
the  interior  of  the  mass  of  liquid,  there  will  be  surface  tension  and 
the  two  grains  will  not  come  together  because  this  would  enlarge  the 
surface  area  and  increase  the  number  of  surface  particles  in  the  liquid. 
If,  on  tlie  other  hand,  the  potential  of  the  particle  on  the  surface  of 
the  liquid  is  greater  than  the  potential  of  a  particle  in  the  interior  of 
the  liquid  mass,  the  surface  will  tend  to  enlarge  and  the  grains  of 
clay  may  come  close  together  and  be  held  there  with  some  force,  as 
their  close  contact  increases  the  number  of  surface  particles  in  the 
liquid  around  them.  This  probably  explains  the  phenomenon  of 
tiocculation,  a  phenomenon  of  great  importance  in  agriculture. 

Muddy  water  may  remain  turbid  for  an  indefinite  time.  If  a  trace 
of  lime  or  salt  be  added  to  the  water  the  grains  of  clay  focculate, 
that  is,  they  come  together  in  loose,  light  iiocks,  like  curdled  milk, 
and  settle  quickly  to  the  bottom,  leaving  the  liquid  above  them  clear. 
Ammonia  and  some  other  substances  tend  to  prevent  this  and  to  keep 


EXPERIMENT    STATION.  25'D 

the  grains  apart,  or  to  push  them  apart  if  flocculation  has  already 
taken  place.  This  is  similar  to  the  precipitation  of  some  solid 
matters  from  solution.  When  lime  is  added  to  a  filtered  solution  of 
an  extract  of  stable  manure,  the  organic  matter  is  precipitated  in 
similar  loose,  bulky  masses. 

It  will  be  remembered  that  there  is,  on  an  average,  about  50  per 
cent,  by  volume  of  empty  space  in  the  soil.  This  empty  space  is 
divided  up  by  a  vast  number  of  grains  of  sand  and  clay.  If  these 
grains  are  evenly  distributed  throughout  the  soil,  so  that  the  separate 
spaces  between  the  grains  are  of  nearly  uniform  size,  water  will  move 
more  slowly  through  the  soil  than  if  the  grains  of  clay,  through 
flocculation,  adhered  closely  together  and  to  the  larger  grains  of  sand, 
making  some  of  the  spaces  larger  and  otliers  exceedingly  small. 

We  have,  then,  this  principle  to  work  on  in  the  improvement  of 
soils.  In  a  close,  tight  clay,  through  which  water  moves  slowly,  the 
continued  use  of  lime  may  cause  flocculation,  the  grains  of  clay  may 
move  closer  together,  leaving  larger  spaces  for  the  water  to  move 
through.  On  the  other  hand,  there  are  soils  in  which  the  clay  is  held 
so  closely  to  the  grains  of  sand  as  to  give  tlie  soil  all  the  appearance 
and  properties  of  a  sandy  soil,  although  there  is  as  much  clay  present 
as  in  many  a  distinctively  "  clay  soil." 

Again,  in  a  light  sandy  land,  lime  may  precipitate  the  organic 
matter  from  solution  within  the  soil,  in  light,  bulky  masses,  which 
will  All  up  the  spaces  and  retard  the  rate  of  circulation  of  water. 

And  so,  if  judiciously  used,  lime  may  be  the  "best  fertilizer"  for 
a  light  sandy  soil  or  for  a  heavy  clay  land.  In  the  one  case,  there 
must  be  sufhcient  organic  matter  for  the  lime  to  act  on  or  it  will 
injure  the  soil ;  in  the  other  case,  there  is  no  such  need  of  organic  matter 
in  liming  a  tight  clay  soil,  and  too  much  of  it  may  be  decidedly 
injurious. 

We  will  speak  of  this  more  at  length  when  we  come  to  speak  of 
the  application  of  these  principles  to  the  improvement  of  soils. 

III.  The  Volume  of  Empty  Space  in  Soils. 

There  is,  on  the  average,  about  50  per  cent,  by  volume  of  empty 
space  in  the  soil.  The  amount  in  the  soil  proper  will  vary  with  the 
stage  and  state  of  cultivation,  but  the  "empty  space  in  the  undisturbed 
subsoil  will  remain  fairly  constant.  The  amount  of  space  has  not 
been  determined  in  the  soils  of   Maryland,  for   the   determination 


260  MARYLAND    AGRICULTURAL 

requires  that  an  exact  volume  of  soil  be  removed  from  the  field,  and 
this  takes  much  time  and  careful  work.  This  will  be  made  the 
subject  of  some  future  investigation,  and  for  the  present  our  work 
must  be  based  upon  determinations  which  have  been  made  elsewhere. 
The  amount  of  space  has  been  determined  in  a  number  of  subsoils 
in  South  Carolina,  in  their  natural  position  in  the  field,  taking  in  a 
wide  range  of  soil  formations.  The  per  cent,  bj  volume  of  empty 
space  is  given  in  the  table  following. 

Table  2: — Empty  Space  in  So.  Ca.  Subsoils. 
Per  Cent,  hy    Volume. 

78.  Wedgefield,  (sandy  laud) 41.80 

QQ.  Gourdins 42.82 

57.  Sumter 44.10 

80.  Lesesne 46.41 

57a.  Sumter 47.70 

69.  Gourdins,  (Mr.  Roper) 49.74 

64.  Lanes 50.00 

74.  Wedgefield,  ("Red  Hill"  formation) 50.03 

69a.  Gourdins 50.25 

53.  Charlotte,  N.  C 52.05 

71.  Gourdins,  ("Bluff  land") 55.40 

53a.  Charlotte,  K  C 57.19 

76.  Wedgefield,  ("gummy  land") 58.46 

76a.  Wedgefield,  ("gummy   land") 61.54 

42.  Chester,  ("pipe  clay") 05.12 

The  first  six  subsoils,  which  may  be  considered  essentially  sandy, 
have,  on  the  average,  45.43  per  cent,  by  volume  of  empty  space. 
The  remaining  nine  subsoils,  which  are  from  essentially  clay  lands, 
have,  on  the  average,  55.55  per  cent,  by  volume  of  empty  space. 

In  "How  Crops  Feed,"  Johnson  gives  the  weight  of  a  cubic  foot 
of  sandy  soil   as  110  pounds,  and  of  a  cubic  foot  of  a  clay  soil  as  75 


EXPERIMENT    STATION.  261 

pounds.  This  would  give  about  34  and  55  per  cent,  by  volume  of 
empty  space,  respectively,  in  these  soils. 

It  is  unfortunate  that  the  term  "light  soil"  has  become  commonly 
applied  to  that  which  actually  weighs  a  good  deal  more  tlian  an 
equal  bulk  of  what  is  called  "heavy  soil." 

In  our  own  work,  unless  the  actual  determinations  have  been 
made,  we  have  assumed  that  the  subsoil  of  "light  sandy  land"  has 
45  per  cent,  by  volume  of  empty  space,  and  that  of  a  strong  clay 
land,  55  per  cent.  If  all  the  space  within  these  soils  was  filled  with 
water,  they  would  contain  22.41  and  31.55  per  cent,  hy  weight  of 
water,  respectively. 

For  the  empty  space  in  our  soil  types,  to  be  presently  desc  ribed, 
we  have  assigned,  as  probable,  values  based  on  this  South  Carolina 
work. 

lY.  The  Relation  of  Geology  to  Agkicultuke. 

We  shall  use  in  this  report  certain  geological  names  which  may  be 
unfamiliar  to  many  of  our  readers,  and  it  seems  well  to  insert  a  sec- 
tion explaining  the  reason  for  this  and  the  general  relation  of  geology 
to  agriculture. 

We  shall  show  presently  that  there  are  well-marked  types  of  soil  in 
tliis  State ;  some  suited  to  grass  and  wheat,  others  to  wheat  but 
rather  light  for  grass,  others  to  tobacco,  truck,  or  left  out  as  barren 
wastes.  The  texture  and  general  appearance  of  these  soils  differ  very 
much  so  that  one  can  tell  at  a  glance  to  what  kind  of  crop  each  of 
these  types  is  best  adapted.  We  shall  show  further,  that  from  this  differ- 
ence in  texture,  which  is  so  very  apparent  to  the  eye,  there  is  a 
marked  difference  in  the  relative  rate  with  which  water  moves  within 
the  soil,  and  the  ease  with  which  the  proper  amount  of  water  may  be 
maintained  and  supplied  to  the  crop. 

As  crops  differ  in  the  amount  of  water  which  they  require,  and  in 
the  amount  of  moisture  in  the  soil  in  which  the}^  can  best  develop, 
this  difference  in  the  relation  of  these  soil  types  to  water  probably 
accounts  for  the  local  distribution  of  plants. 

In  green-house  culture  the  same  kind  of  soil  is  used  for  all  kinds  of 
plants,  but  great  judgment  is  rec|uired  in  watering  the  plants.  Some 
plants  require  a  very  wet  soil,  others  must  be  kept  quite  dry.  The 
amount  of  water  required  will  not  be  the  same  at  different  stages  of 
development  of  the  plant.     During  the  earlier  growing  period    the 


262  MARYLAND    AGRICULTURAL 

soil  is  kept  quite  wet,  but  during  the  fruiting  or  flowering  period 
the  soil  is  kept  much  drier.  Each  class  of  plants  requires  in  this 
way  special  treatment,  and  it  is  through  this  judicious  control  of  the 
water  supply  in  the  soil  and  the  temperature  of  the  air,  that  the 
best  development  of  each  class  of  plants  is  attained. 

Our  soil  types,  therefore,  in  having  different  relations  to  the  circu- 
lation of  water,  partake  somewhat  of  these  artificial  conditions  in 
green-house  culture,  and  on  each  of  them  certain  classes  of  plants  will 
find  conditions  of  moisture  best  suited  to  their  growth  and  develop- 
ment. 

Our  soils  have  been  formed  from  the  disintegration,  or  decay,  of 
rocks.  The  crystalline  rocks,  such  as  granite,  gabbro  and  serpentine, 
from  which  the  soils  of  Northern  Central  Maryland  are  derived,  have 
been  formed  by  the  slow  cooling  of  the  earth's  crust.  They  are 
made  up  of  different  minerals,  the  most  common  of  which  are  quartz, 
feldspar  and  mica,  cemented  together  usually  with  lime  or  silica. 
The  kind  of  rock  is  determined  by  the  kind  and  relative  amount  of 
each  of  these  minerals  of  which  it  is  made.  When  the  rocks  decay, 
the  cementing  material  is  dissolved  and  carried  off,  and  many  of  the 
minerals  themselves  are  changed.  Now,  the  texture  or  the  relative 
amount  of  sand  and  clay  contained  in  the  soil  resulting  from  the  dis- 
integration of  these  rocks,  will  depend  upon  the  kind  of  rock,  that  is, 
upon  the  minerals  of  which  it  was  composed. 

The  material  resulting  from  the  disintegration  of  these  rocks  is 
slowly  washed  away  and  carried  off  by  streams  and  rivers.  As  the  cur- 
rent of  water  becomes  slower  near  the  sea,  the  sand  is  deposited  along 
a  rather  narrow  shore  line,  while  the  finer  particles  of  clay  are  carried 
further  and  deposited  over  wider  areas.  The  conditions  where  some 
parts  of  this  material  are  being  deposited  may  be  favorable  to  the 
o-rowth  of  coral  and  of  various  kinds  of  shell-fish,  so  that  their  re- 
mains accumulate  in  beds  of  great  thickness,  giving  the  material  for 
the  limestone  of  the  present  day.  These  sediments  are  thus  assorted 
out  by  subsidence  in  water  of  different  velocities,  as  though  they  had 
been  sifted  and  the  different  grades  of  material  spread  out  over  wide 
areas. 

The  sediments,  being  slowly  deposited  in  beds  of  great  thickness, 
are  converted  into  rocks  through  the  agency  of  heat  and  great 
pressure  to  which  they  are  subjected  by  the  accumulation  above,  and 
so  sandstones,  limestones  and  shales  have  been  formed;  the  sandstone. 


EXPERIMENT    STATION.  263 

where  the  coarser  material  has  been  deposited  near  the  shore ;  the 
limestone,  where  the  shells  have  accumulated  ;  and  the  shale,  where 
the  line  nind  has  been  spread  out  over  a  wider  area  of  still  water. 

It  is  from  the  disintegration  of  these  "sedimentary"  rocks,  as  they 
are  called,  which  have  since  been  raised  above  the  surface  of  the 
water,  that  the  soils  of  Western  Maryland  have  been  formed.  There 
are  the  limestone  valleys,  where  shell-fish  were  once  abundant,  and 
Avhere  now  is  a  strong  clay  soil,  well  adapted  to  grass  and  wheat ; 
the  sandstone  ridges,  some  of  which,  resisting  decay,  form  the 
mountain  ranges,  while  others,  made  of  finer  grains  of  sand  and  less 
firmly  cemented  together,  form  some  of  the  fertile  hill  and  valley 
lands ;  the  shales,  in  which  the  grains  of  rand  were  so  extremely 
small  that  they  adhere  so  closely  to  each  other  that  tliey^  do  not 
thoroughly  disintegrate,  and  the  soil  is  filled  with  fragments  of  the 
rock  and  supports  but  a  scanty  mountain  pasture. 

The  soils  of  Southern  Maryland  and  the  Eastern  Shore  are  of  more 
recent  origin.  The  sediments  have  not,  as  yet,  been  subjected  to  the 
great  heat  and  pressure  required  in  rock-making,  and  they  are  still 
in  the  first  stages  of  formation. 

Now,  geology  defines  the  limits  and  areas  of  these  different  forma- 
tions and  of  these  different  rocks,  and,  as  I  have  shown,  that  these 
rocks  determine  the  texture  of  the  soil,  a  thorough  and  detailed 
geological  map  of  the  State  should  answer  for  a  soil  map.  Any  one 
familiar  with  the  texture  of  the  soil,  or  kind  of  soil,  formed  by  the 
disintegration  of  granite,  gabbro,  and  the  different  kinds  of  lime- 
stones, sandstones  and  shales,  should  be  able  to  tell  by  a  glance  at  the 
map  the  position  and  area  of  each  kind  of  soil.  Each  color  on 
the  map  would  represent  a  soil  forma,tion  of  a  certain  texture,  in 
which  the  conditions  of  moisture,  under  our  prevailing  climatic  con- 
ditions, would  be  best  adapted  to  a  certain  crop. 

Such  a  geological  or  soil  map  would  be  of  the  greatest  aid  to  any 
one  interested  in  the  agricultural  lands  of  the  State.  It  seems  to  me 
that  such  a  map  of  the  soil  formations  in  this  State  would  be  of  great 
benefit  to  agriculture  in  the  hands  of  farmers  and  of  those  interested 
in  immigration  and  in  the  material  advancement  of  the  agricultural 
interests  of  the  State.  Kot  only  so,  but  I  think  the  interest  of  this 
work  demands  the  most  thorough  and  detailed  geological  survey  so 
that  each  of  these  soil  formations  may  be  carefully  located  and  out- 
lined.    The    wheat,  tobacco,   truck   and    barren    lands   of    Southern 


264  MA.RYLAND    AGRICULTURAL 

Maryland  are  each  confined  to  certain  different  geological  formations 
for  their  best  development,  and  a  geological  map  of  this  portion  of  the 
State  should  show  the  area  and  distribution  of  the  lands  best  adapted 
to  these  crops. 

There  is  usually  some  marked  and  distinctive  botanical  character 
in  the  herbage  of  these  different  soil  formations.  We  have  pine 
barrens,  white  oak  lands,  black  jack  lands,  chinquapin  lands,  grass 
lands,  wheat  lands  and  truck  lands.  These  names  convey  a  very  good 
impression  of  the  character  and  texture  of  the  soil,  and  they  should 
be  more  generally  used.  When  a  soil  formation  is  spoken  of  as 
black  jack  land,  the  name  conveys  a  distinct  impression  of  the  kind  of 
soil,  for  a  soil  must  have  a  certain  characteristic  texture  to  produce 
such  a  growth. 

We  have  not  been  able  to  include  this  botanical  work  on  the 
different  soil  formations  of  the  State  this  year,  but  it  will  be  made  a 
subject  of  careful  investigation.  In  the  mean  time  and  until  a  de- 
scription better  suited  to  the  agricultural  interests  can  be  giv^en,  the 
geological  names  will  have  to  be  used  to  designate  these  different  soil 
formations. 

y.  Soil  Types. 

The  soils  of  the  State  appear,  at  first  sight,  to  offer  an  endless 
field  of  research  in  the  great  variety  often  seen  on  a  single  farm  and 
in  the  same  field,  but  a  more  comprehensive  view  of  the  matter  will 
show  this  to  be  due  to  local  causes,  which  have  mixed  up  and  modi- 
fied the  original  soil  formation.  These  local  modifications  may  be 
neglected  for  the  present,  until  the  general  features  of  the  repre- 
sentative soils  of  the  region  have  bteen  worked  out. 

The  characteristic  properties  of  great  soil  formations,  or  soil  types, 
must  first  be  determined,  and  then  more  detailed  work  may  be  done 
in  the  examination  of  soils  of  local  interest.  Why  will  not  truck, 
tobacco,  wheat  and  grass  grow  equally  well  on  all  soils?  It  is  not  so 
much  a  matter  of  plant  food  as  of  the  texture  of  the  soil.  'No  addi- 
tion of  mere  plant  food  in  the  form  of  fertilizers  or  manure  will 
change  at  once  a  light  sandy  soil  into  a  good  wheat  land.  It  takes  no 
very  great  experience  to  tell  at  a  glance  the  condition  of  a  soil,  and 
to  what  class  of  plants  it  is  best  adapted.  It  is  from  the  ajpjpearance 
of  the  soil,  that  is,  from  the  texture  and  structure,  that  this  judgment 
is  formed. 


EXPERIMENT    STATION.  265 

This  is  the  key  to  soil  investigations.  It  is  not  until  this  problem 
has  been  mastered  and  these  very  evident  differences  in  soils  have 
been  explained,  that  the  real  and  full  value  and  application  of  the 
chemical  determinations  in  plants  and  soils  will  be  seen.  As  a  rule, 
the  chemical  analysis  of  a  soil  will  not  enable  a  farmer  to  determine 
to  what  his  land  is  best  adapted ;  but,  on  the  contrary,  the  farmer, 
from  his  experience  and  judgment,  must  inform  the  chemist  on  this 
point,  and  must  tell  him  of  the  strength  and  condition  of  the  land. 

What  are  the  characteristic  properties  of  a  good  wheat  land,  of  the 
best  tobacco  soil,  of  the  best  grass  land,  of  the  best  land  for  market 
truck  ?  What  is  it  in  the  appearance  of  a  soil  which  enables  a  farmer 
to  place  it  in  one  or  the  other  of  these  classes  ?  The  truck  lands  of 
Southern  Maryland  are  "lighter"  in  texture  than  the  best  tobacco 
lands,  and  still  "lighter"  than  the  best  wheat  lands.  The  wheat 
lands  of  Southern  Maryland  are  "  lighter "  than  the  grass  and  wheat 
lands  of  I^^orthern  and  Western  Maryland. 

It  is  only  after  the  characteristic  properties  of  a  number  of  soils 
of  well  marked  agricultural  value  have  been  carefully  determined 
that  we  may  hope,  by  examination  and  comparison,  to  suggest  meth- 
ods for  the  improvement  of  other  soils  of  local  interest.  We  must 
have,  first  of  all,  a  basis  of  comparison  in  well  known  and  represen- 
tative soils. 

We  have  made  several  extended  trips  into  Southern  and  Western 
Maryland,  collecting  a  large  number  of  samples  of  soils  and  sub-soils 
of  representative  agricultural  value  and  importance.  These  samples 
have  been  arranged  in  groups,  according  to  their  agricultural  value 
and  their  geological  origin ;  and  equal  weights  of  the  samples  in  each 
group  have  been  mixed  together,  forming  a  composite  sample  repre- 
senting the  type  of  the  soil  formation.  We  have,  in  this  way,  classi- 
fied the  soils  of  all  the  principal  agricultural  regions  of  the  State,  and 
they  are  represented  by  comparatively  very  few  type  samples,  as 
shown  in  the  following  table : 

The  formations  are  not  given  in  the  order  of  their  geological  origii^ 
but  according  to  their  agricultural  importance  and  distribution. 


266 


MARYLAND    AGKICULTURAL 


Table  3 : — Soil  Types  in  Maryland. 

Sample. 

Soils  adapted  to, 

Localities. 

Geological  formation. 

276. 

Pine  barrens. 

*(2) 

Lafayette, 

283-4. 

Market  truck. 

(6-8) 

Eocene. 

285-6. 

Tobacco. 

(9-9) 

Neocene. 

279-80. 

Wheat. 

(7-14) 

Neocene. 

277-8. 

Wheat    soil   of    river 
terraces. 

(5-5) 

Columbian  terrace. 

Barren  clay  hills. 

Potomac. 

Grass  and  wheat. 

Trenton  chazy  limestone. 

287-8. 

Grass  and  wheat. 

(2-4) 

Helderberg  limestone. 

238. 

Grass  and  wheat. 

(1) 

Catskill. 

281-2. 

Grass  and  wheat. 

(4-5) 

Triassic  red  sandstone. 

290. 

Mountain  pasture. 

(3) 

Oriskany, 

289. 

Poor  mountain  pasture. 

(6) 

Chemung,  Hamilton,  Ni- 
agara, Clinton. 

The  Lafayette,  Eocene,  Neocene  and  Columbian  terrace  formations 
occur  in  Southern  Maryland;  the  Potomac  formation  is  a  narrow 
belt  extending  across  the  State  on  the  line  of  the  B.  and  O,  and  the 
B.  and  P.  railroads;  the  Trenton  chazy  limestone  forms  the  Frederick 
and  Hagerstown  Valleys;  the  Triassic  red  sandstone  covers  a  con- 
siderable area  to  the  north  and  south  of  the  Frederick  Valley;  the 
Helderberg  limestone,  Catskill,  Oriskany,  Chemung,  Hamilton,  Ni- 
agara and  Clinton  formations  form  the  valleys,  hills  and  mountains 
of  Western  Maryland. 

In  the  Piedmont  Plateau  of  Northern  Central  Maryland,  there  are 
grass  and  wheat  soils  from  gneiss,  granite,  gabbro  and  limestone; 
wheat  and  tobacco  soils  from  mica  schist;  corn  lands  from  sandstone; 
and  barren  hills  from  serpentine. 

There  has  been  no  opportunity  this  year  to  collect  samples  of  soils 
from  the  Eastern  Shore, 

There  are  two  or  three  mountain  formations  wliich  occur  in  such 
small  areas  that  their  soils  have  not  been  considered  here.  The  coal 
formation  is  so  uneven,  with  its  succession  of  sandstones,  limestones 


EXPERIMENT    STATION.  267 

and  shales,  whicli  have  not  been  separated  on  the  geological  map, 
that,  although  it  is  of  importance  from  covering  a  large  area,  it  has 
not,  as  yet,  been  considered. 

The  coarse  sands  of  the  quarternarj  formation,  covering  the  ex- 
treme lower  part  of  the  State,  have  not  been  sampled. 

In  the  table,  where  a  double  number  is  given,  the  first  number  re- 
fers to  the  sample  of  soil,  and  the  second  number  to  the  subsoil. 
Where  a  single  number  is  given  for  a  type,  there  is  no  perceptible 
difEerence  between  the  soil  and  subsoil  in  the  localities  visited. 

The  iigures  in  brackets  under  *  give  the  number  of  localities  from 
which  samples  were  taken  to  make  up  the  samples  of  type  soils  and 
subsoils. 

The  grass  and  wheat  soils  of  the  different  types  in  the  Piedmont 
Plateau  and  Western  Maryland  differ  in  texture  and  in  relative  fer- 
tility, and  should  be  distinguished  by  different  botanical  characters, 
but  for  the  present  the  geological  names  will  be  used  to  designate 
them. 

The  truck,  limestone  and  Catskill  lands  are  important  soils,  which 
should  have  moi'e  localities  represented  in  the  type  samples. 

To  establish  a  type,  samples  should  be  taken  from  as  many  locali- 
ties as  possible;  from  ten  localities  at  least,  even  in  as  small  a  State 
as  Maryland.  The  type  sample  is,  therefore,  a  sort  of  composite 
sample  made  by  mixing  equal  weights  of  samples  from  a  number  of 
localities  in  each  formation. 

A  description  of  the  samples  tliemselves  will  be  given  later.  They 
were  taken  with  a  spade,  or  auger,  the  soil  being  taken  down  to  the 
change  of  color,  and  the  subsoil  below  this  to  a  depth  depending 
upon  the  nature  and  depth  of  the  material,  usually  12  to  18  inches. 

The  soil  of  the  pine  barrens  is  a  coarse  yellow  sand,  very  loose 
and  incoherent  when  worked,  but  packed  exceedingly  hard  and  tig'ht 
■  in  the  subsoil.  The  lands  are  very  infertile.  These  soils  should  be 
more  carefully  examined,  and  more  samples  of  them  should  be  taken 
for  our  type  sample,  as  they  cover  such  an  extensive  area  in  Soutliern 
Maryland  with  pine  barrens,  which  will  some  day,  when  agricultural 
lands  rise  in  value,  have  to  be  taken  up  and  improved. 

Most  of  the  truck  supplied  to  the  Baltimore  and  the  larger  North- 
ern markets,  from  this  State,  is  produced  on  a  rather  narrow  belt 
bordering  the  Bay  and  rivers  from  Baltimore  south  to  West  Eiver. 
This  area  is  largely  in  the  eocene  formation,  although  far  down  on 


268  MARYLAND   AGKICULTUEAL 

the  river  necks  the  lands  are  coarser  and  belong  to  a  more  recent 
formation. 

The  truck  lands  proper  are  a  fine  textured,  grey  or  reddish  grey, 
sand.  They  are  naturally  fertile,  but  require  care  to  keep  up  their 
fertility.  The  texture  of  l^ie  soil  admits  of  vast  quantities  of  manure 
and  organic  refuse  being  used  for  forcing  the  vegetables,  without  fear 
of  clogging  the  soil.  The  texture  of  these  lands  adapt  them  well  to 
the  requirements  of  market  gardening. 

The  soils  are  derived  from  the  weathered  green  sands,  similar  in 
composition  to  the  green  sand  marls  of  Kew  Jersey,  so  that  in  chemi- 
cal composition  they  should  be  rich  in  potash  and  phosphoric  acid. 

The  soils  are  too  light  in  texture  for  wheat,  although,  in  the  high 
state  of  cultivation  to  which  they  are  brought  for  market  truck,  good 
crops  of  wheat  may  be  produced,  but  at  such  a  cost,  and  under  such 
artificial  conditions,  that  the  soil  cannot,  in  any  sense,  be  called  a 
wheat  soil. 

Samples  have  been  taken  from  too  few  localities  in  the  truck  area 
to  make  the  type  samples  of  soil  and  subsoil  (Nos.  283-4)  perfectly 
satisfactor3^  They  are  probably  heavier  than  the  best  type  of  truck 
land.  The  collection  of  these  samples  has  been  rather  incidental  to 
other  work,  as  most  of  our  attention  has  been  given  this  year  to  the 
tobacco  and  wheat  soils  of  Southern  Maryland.  The  great  truck 
area  between  Baltimore  and  Annapolis  is  not  represented  in  these 
samples. 

The  best  tobacco  and  wheat  lands  in  Southern  Maryland,  apart  from 
the  river  terraces,  seem  to  be  confined  to  the  diatomaceous  earth 
horizon  of  the  neocene  formation,  or  of  a  later  formation  made  over 
out  of  this  same  material.  The  formation  extends  obliquely  across 
the  peninsula,  in  rather  a  broad  belt  from  South  River  and  Herrino- 
Bay  to  Pope's  Creek  on  the  Potomac  River. 

The  subsoil  of  the  wheat  land  is  a  strong  clay -loam  of  a  very 
marked  and  characteristic  texture  and  yellow  color.  It  is  usually  not 
more  than  4  to  6  feet  deep,  resting  directly  on  the  white  diatomaceous 
earth,  and  appears  to  be  formed  from  this  by  weathering,  as  there  is 
no  distinct  line  of  separation.  The  samples  of  both  wheat  and  tobacco 
subsoils  still  contain  many  diatoms.  The  weathering  of  this  diato- 
maceous earth  probably  takes  place  quite  rapidly  on  exposure,  and 
some    interesting    changes    occur,    including   a   local   accumulation 


EXPERIMENT    STATION,  269 

of  clay  in  the  yellow  subsoil,  which  should  be  further  studied.  We 
have  the  material  for  this  work,  but  it  has  not  been  worked  out  yet. 

Wheat  and  tobacco  are  commonly  grown  on  the  same  land  in  alter- 
nate years  or  in  longer  rotation,  but  the  strongest  and  best  wheat  land 
is  too  heavy  for  tobacco.  It  gives  a  large  yield  but  makes  a  coarse, 
thick  tobacco  leaf  which  is  sappy  and  cures  green  and  does  not  take 
on  color.  The  best  class  of  tobacco  lands,  where  the  finest  grade  of 
tobacco  is  produced,  is  of  lighter  texture  and  too  light  for  the  best 
wheat  production.  The  best  tobacco  soils  around  Upper  Marlboro 
appear  to  be  at  a  lower  elevation  than  the  strongest  wheat  lands,  and 
are  rather  heavier  in  texture  than  the  better  grade  of  tobacco  lands  in 
the  ]^ottingham,  Aquasco  and  Chaneyville  regions.  These  latter  are 
more  loamy,  although  they  are  still  over  very  pure  deposits  of  diat- 
om aceous  earth. 

At  a  road  cut  near  Upj3er  Marlboro  there  is  an  exposure  of  diato- 
maceous  earth,  probably  30  or  50  feet  deep.  The  upper  part  of  this 
exposure  is  very  pure  white  earth,  very  light  and  porous,  A  strong 
wheat  subsoil  rests  directly  on  this.  The  lower  part  of  the  exposure 
is  decidedly  more  sandy  in  texture,  and  more  like  the  typical  tobacco 
land.  The  lighter  texture  of  the  tobacco  soils  may  be  due  to  local 
modifications  of  original  wheat  lands,  or  they  may  themselves  turn 
into  good  wheat  soils  by  further  weathering,  or  these  tobacco  lands 
may  belong  to  a  different  horizon  of  the  diatomaceous  earth  form- 
ation. The  last  seems  very  probable,  but  it  may  be  due  to  different 
causes  in  different  localities. 

Lime  is  the  great  fertilizer  for  all  classes  of  soils  in  this  region. 
On  the  lighter  soils  lime  must  be  used  only  with  organic  matter,  or  it 
will  "burn  out  the  land."  Lime  every  five  years,  and  clover,  will 
keep  up  their  wheat  lands.  But  this  rule  is  being  neglected.  Lime 
is  applied  more  i-arely  and  the  lands  are  becoming  clover-sick.  The 
wheat  and  tobacco  lands  are  deteriorating.  This  cannot  be  due  solely 
to  a  loss  of  plant  food  from  the  soil,  for  there  is  undoubtedly  a  change 
of  texture  of  the  soil,  very  apparent  to  the  eye,  which  must  change 
the  relation  of  the  soil  to  the  circulation  of  water  and  to  crop  pro- 
duction. What  these  changes  are  which  take  place  in  the  soil,  must 
be  fully  investigated  and  must  be  well  understood  before  the  most 
intelligent  methods  can  be  proposed  for  the  recovery  and  improve- 
ment of  the  lands. 

The  fertile  terraces  bordering  the  rivers  of  Southern  Maryland  are 
very  level  and  very  uniform  in  appearance.     They  extend  about  half 


270  MARYLAND   AGRICULTUKAL 

a  mile  inland  from  the  rivers.  The  soil  is  a  fine  grained  loam  and 
the  subsoil  a  jellow  clay  loam.  It  would  be  classed  as  a  good  strong 
wheat  soil,  very  easily  worked  and  naturally  very  fertile  and  capable 
of  the  highest  state  of  cultivation.  They  ai-e  similar  in  appearance 
to  the  "ridge  lands"  of  the  south.  Recently  the  fertile  valley  lands 
along  the  B.  &  O.  R.  E,.,  between  Baltimore  and  Washington,  (here- 
tofore considered  part  of  the  Potomac  formation,)  as  well  as  other 
lands  in  the  vicinity  of  Baltimore,  have  been  classed  with  the  Colum- 
bian terrace  formation,  but  these  localities  are  not  represented  in  our 
type  samples. 

The  barren  clay  hills  crossing  the  State  in  a  broad  belt  from  Wash- 
ington, along  the  two  railroads,  to  the  Delaware  line,  belonging  to  the 
Potomac  formation,  have  not  been  sampled. 

The  fertile  soils  of  the  Frederick  and  Plagerstown  Yalleys,  formed 
by  the  disintegration  of  the  Trenton  limestone,  are  very  heavy,  red 
clay,  well  suited  to  grass  and  wheat.  They  are  much  stronger  than 
the  wheat  lands  of  Southern  Maryland.  It  takes  a  strong,  heavy  soil 
for  grass  and  these  are  naturally  good  grass  lands.  We  have  a 
number  of  samples  from  different  localities  but  not  enough  to  make  a 
satisfactory  type  sample. 

The  Triassic  red  sandstone  covers  a  considerable  area  to  the  north 
and  south  of  the  limestone  formation  in  the  Frederick  valley,  with  a 
dark,  Indian  red,  heavy  clay  soil.  It  is  very  productive  but  is  not  so 
safe  or  certain  as  the  limestone  soil.  Like  the  limestone  soil,  it  is 
greatly  benefited  by  an  application  of  lime. 

The  Helderberg  limestone  (cement  rock)  forms  a  small  area  of 
fertile  hill  and  valley  lands  west  of  Hagerstown.  The  subsoil  is  a 
strong  yellow  clay,  naturally  well  drained,  and  capable  of  a  high 
state  of  cultivation.     The  land  is  well  adapted  to  grass  and  wheat. 

The  soil  appears  very  uniform  in  texture  and  the  type  sample  is 
considered  fairly  satisfactory. 

The  Catskill  formation  gives  a  very  strong  soil,  well  suited  to  both 
grass  and  wheat.     It  has  a  very  characteristic  dark  red  color. 

The  other  formations  are  found  in  narrow  belts  forming  the  hills 
and  mountain  ranges,  and,  so  far  as  I  have  seen,  they  are  generally 
very  poor  and  stony.  There  is  often  no  perceptible  difference 
between  the  soil  and  subsoil  of  these  mountain  formations,  and  where 
they  cannot  be  distinguished,  a  sample  is  taken  down  to  12-18  inches 
and  classed  with  the  subsoils. 


EXPERIMENT    STATION.  271 

A  description  of  the  soils  and  subsoils  whioh  Jiave  been  used  to 
mahe  ttp  the  type   samples. 

Pine  Barrens. 

"276.  Type  sample  from  the  following  localities : 

209.  Coarse  jellow  sand  and  gravel  overlying  neocene  at  Cove  Point, 

three  miles  north  of  Drum  Point. 

210.  Coarse  jellow  sand  from  bluff  at  Jones'  wharf,  Patnxent  River. 

Truck   Land. 
'283.  Type  sample  of  soil  frorru  the  folloioing  localities : 

144.  Sandy  soil  from  Patuxent,  near  Governor's  Bridge.     Naturally 

rather  poor  and  unproductive  but  would  make  good  truck  and 
is  typical  watermelon  land. 
167.  Sandy  soil  from  a  peach  orchard  at  Mitchell ville. 

170.  Soil  of  light  lands  west  of  Hall's  Station.     From  the  farm  of 

J.  Berry.  Yery  characteristic  truck  land  and  of  considerable 
area  here. 

267.  Soil  of  truck  land  from  farm  of  J.  Birch,  South  River  Neck. 

269.  Sandy  soil  of   truck  land.  South  River  Neck. 

271.  Soil  of  truck  land  east  of   Hill's  Bridge. 

284.  Type   sample   of  subsoil  from   the  following   localities: 

145.  Sandy  subsoil  from  near  Governor's  Bridge.     Under  144. 

158.  Subsoil  of  pine  land  on  the  "Ridge  road"  near  Cheltenham, 
A  compact  red  sand  which  should  make  good  truck  land. 
There  is  a  large  area  of  this  land  here,  probably  of  Lafayette 
or  possibly  of  neocene  origin. 

166.  Subsoil  from  B.  D.  Mullikin's  farm,  between  Hall's  Station  and 
Mitchellville.  Characteristic  truck  land  of  that  region,  show- 
ing green  grains  of  glauconite  and  of  undoubted  eocene  origin. 

169.  Subsoil  from  peach  orchard  at  Mitchellville,  from  nnder  167. 

171.  Subsoil  of  light  lands  west  of  Hall's  Station,  under  170. 

268.  Subsoil  truck  land,  from  under  267,  from  the  farm  of  J.  Bir  cli 

South  River  Neck. 

270.  Subsoil  of  truck  land,  from  under  269,  South  River  Neck. 

272.  Subsoil  truck  laud,  from  under  271,  east  of  Hill's  Bridge. 

These  soils  and  subsoils  are  undoubtedly  of  eocene  origin 
except  158,  and  possibly  269  and  270,  which  were  far  down  on 
the  Neck  and  may  be  of  more  recent  origin. 


272  makyland  agricul'iueai, 

Tobacco  Land. 
^85.  Type  sample  of  ^o\\,froin  the  following  localities: 

146.  Soil  from  Clias.  W.  Sellman's  farm  near  Davidsonville. 

Rather  light  for  wheat  but  makes  good  tobacco  and  corn. 

161.  Loam  soil  from  J.  H.  Sasscer's  farm  near  Upper  Marlboro.  A 
deep  loam,  lying  rather  low  and  much  lighter  than  the  best 
wheat  lands.  It  is  a  fair  type  of  the  tobacco  lands  of  Marl- 
boro district,  but  is  rather  heavy  for  tobacco,  making  rather  a 
heavy,  coarse  leaf.  It  is  heavier  than  the  I^Tottingham  or 
Chaneyville  tobacco  lands  Wheat,  on  this  land,  is  inclined  to 
go  to  straw  and  not  produce  much  grain. 

163.  Soil  of  H.  H.  Sasscer's  tobacco  land,  North  Keys.  Considered 
rather  heavier  than  the  best  type  of  Nottingham  tobacco  land. 
It  makes  a  very  fine  grade  of  tobacco. 

255.  Loam  soil  from  W.  H.  Hopkins,  Bristol.  Light  in  texture  and 
a  very  iine  quality  of  tobacco  land.  Considered  very  fertile 
but  rather  light  for  wheat. 

257.  Soil  of  tobacco  land  from  Fred.  Sasscer's  farm,  Upper  Marlboro. 

259.  Soil  of  tobacco  land  from  the  river  terrace  at  Nottingham.  The 
soil  is  coarser  than  most  of  the  river  terraces  examined.  This 
grade  of  soil  appears  to  be  of  rather  small  area.  The  terraces 
extend  about  half  a  mile  inland  from  the  river  and  produce  a 
fine  quality  of  tobacco. 

261.  Soil  from  a  farm  near  Chaneyville.  It  is  considered  the  very 
finest  grade  of  tobacco  land. 

263.  Soil  of  a  fine  grade  of  tobacco  land  near  Nottingham. 

265.  Soil  of  a  very  fine  type  of  tobacco  land  from  the  farm  of  J.  F. 
Talbott,  Chaneyville. 

286.   Type  sample  of  svhsoil  from  thefollotoing  localities: 

Samples  118,   162,  164,  256,   258,  260,  262,  264,   266,  from 
under  the  soils  just  given,  and  in  the  corresponding  order. 
These  soils  and  subsoils  are  of  neocene  origin  or  formed  of  neocene 

material,  except  259,  260,  263,  264.     Diatoms  were  found  in  most  of 

the  subsoils.     The  finest  tobacco  lands  are  lighter  in  texture  than  the 

best  wheat  lands. 


EXPERIMENT    STATION. 


273 


Wheat  Land. 
'279.   Type  sample  of  9,011. from,  the folloioing  localities  : 

140.  Loam    soil   from   near    Davidson ville,   fairly    representing   the 

wheat  lands  of  this  locality.  It  appears  somewhat  light 
for  wheat,  and  is  not  considered  as  productive  as  it  was 
years  ago.  It  does  not  produce  the  clover  crops  it  once 
did,  which  were  such  an  excellent  preparation  for  wheat. 
The  lands  have  deteriorated.  The  finest  wheat  lands  now  are 
the  hill  lands  where  this  loam  has  not  accumulated,  or  has  been 
removed  by  subsequent  washing,  leaving  exposed  a  yellow  clay 
loam  like  142. 

154.  Clay  soil  from  J.  H.  Sasscer's  farm  near  Upper  Marlboro. 
Yery  line  wheat  land,  similar  to  the  Davidsonville  and  West 
River  lands.  Too  heavy  for  tobacco,  the  plant  being  sappy  and 
curing  green.  These  lands  are  of  considerable  area  around  Marl- 
boro, extending  up  nearly  to  Mitchellville  on  the  east  of  the 
railroad,  and  forming  the  bottom  lands  and  hills,  west  of  the 
Western  Branch  of  the  Patuxent,  but  becoming  much  lighter 
in  texture  south  of  Marlboro. 

178.  Clay  soil  at  the  base  of  the  neocene,  at  Herring  Bay.  Good 
strong  wheat  land,  very  similar  to  the  preceding  localities. 

183.  Soil  of  wheat  land  from  James  Chapman,  Pope's  Creek.  This 
land  carries  a  good  grass  sod. 

249.  Soil  of  wheat  land  from  J.  F.  Talbott,  Chaneyville. 

251.  Soil  of  the  fertile  wheat  lands  of  West  River. 

253.  Loam  soil  from  Mt.  Zion.  Yery  characteristic  wheat  land,  simi- 
lar to  those  of  Davidsonville  and  West  River. 

2W.  Type  sample  of  subsoil  from  the  folloioing  localities : 

141.  Loam  subsoil  from  under  140,  from  near  Davidsonville.     It  has 

good  body  but  not  the  consistancy  of  the  next  sample.     It 
,  fairly  represents  the  lands  around  here  where  washing  has  not 
occurred.     The  loam  is  fi'om  two  to  four  feet  deep. 

142.  Yellow  clay  subsoil  fi'om  under  the  above,  taken  in  a  road  cut- 

This  forms  the  very  best  wheat  land  when  exposed.  It  has 
the  very  characteristic  color  and  texture  of  the  best  wheat 
lands  in  Southern  Maryland. 


274  MARYLAND  AGRICULTURAL 

155.  Clay  subsoil  of  wheat  land  from  under  154,  from  the  farm  of 

J.  H.  Sasscer,  near  Upper  Marlboi"0. 

156.  Yellow  clay  subsoil  under  the  "gravelly  lands"  of  Hosaryville. 

This  is  undoubtedly  neocene  or  neocene  material.  A  fair 
quality  of  diatomaceous  earth  was  found  in  a  road  cut  near  by, 
directly  underlying  this  and  gradually  passing  from  the  white 
earth  into  the  yellow  clay  above.  The  country  is  covered 
generally  with  a  thin  layer  of  fine  gravel,  which  is  hardly 
noticed  in  cultivated  fields  and  is  often  absent.  The  gravel 
extends  down  into  the  undisturbed  clay  and  is  probably  part  of 
the  same  formation,  although  there  may  be  a  light  coating  of 
Lafayette  here,  made  out  of  the  neocene  material.  The  lands 
make  a  very  fine  quality  of  tobacco  but  are  generally  too  light 
for  wheat.  When  this  clay  is  exposed  without  the  gravel, 
however,  it  makes  a  very  fine  wheat  land.  On  Mr.  Holloway's 
place,  between  Rosaryville  and  Woodyard,  and  near  where  this 
sample  was  taken,  they  made  a  very  fair  qualitj^  of  brick  some 
years  ago  from  the  subsoil  of  the  wheat  field. 

179.  Clay  subsoil  of  tlie  wheat  lands  of  Herring  Bay,  from  under  178. 

180.  Yellow  clay  subsoil  from  over  diatomaceous  earth,  from  a  bluff 

three  .miles  north  of  Plum  point. 

181.  Yellow  clay  subsoil  of  wheat  land,  from  under  183,  from  the 

farm  of  James  Chapman,  Pope's  Creek. 
245.  Subsoil  f  wheat  land  opposite  the   church  at  Davidsonville. 
It  is  in  a  fine  state  of  cultivation. 

216.  Subsoil  of  wheat  land  about  one  half  mile  west  of  Davidson- 

ville. 

217.  Subsoil   of  wheat  land,  now  in  grass,  from  the  farm  of  James 

Iglehart,  Davidsonville. 

218.  Subsoil  of  wheat  land  from  the  farm  of  P.  TI.  Israel,  David- 

sonville. 
250.  Subsoil  of  wheat  land  from  the  farm  of  J.  F.  Talbott,  Chaney- 

ville.     From  under  249. 
252.  Subsoil  of  wheat  land,  from  under  251,  South  River. 
254.  Subsoil  of  wheat  land,  from  under  253,  Mt.  Zion. 

PivER  Terrace. 
^77.   Type   sample   of  soil  from   the  following   localities: 
198.  Loam  soil  from  a  wheat  field  opposite  P>enedict. 


EXPERIMENT    STATION. 


2T5 


200.  Loam  soil  from  a  corn  field  below  St.  Mary's.  This  soil  is 
naturally  fertile  and  is  capable  of  great  improvement.  An 
excellent  wheat  soil. 

202.  Loam  soil  from  Mr.  Broome's  wheat  land,  St.  Mary's. 

204,  Loam  soil  from  a  wheat  field  opposite  St.  Mary's.    > 

206.  Loam  soil  from  Clifton  Beach.     Good  wheat  land. 

278.  Tijpe  sain])le  of  subsoil  from  the  following  localities: 
Samples  199,  201,  203,  205,  207,  are  subsoils  from  under  the 
above  soils,  given  in  the  same  order. 

Heldeebeeg    Limestone. 

287.  Tyi?e  sam])le   of  soil  from   the  following   localities: 

221.  Soil  from  near  Hancock.     Very  fertile  grass  and  wheat  land. 

222.  Soil  from  near  Hancock. 

288.  Type   sample   of  subsoil  from   the  following   localities: 
220.  Yery  fertile  grass  and  wheat  land  two  miles  west  of  Hancock, 

No  change  in  18  inches. 

223.  Subsoil  near  Hancock. 

224.  Characteristic    yellow    subsoil   of    the   Helderberg    limestone, 

from   a  wheat  field   two  miles  west   of  Hancock.     Contains 
many  small  fragments  of  undecomposed  rock. 

225.  Subsoil  from  near  Cumberland.     Naturally  rather  poor  but  has 

good  body  and  is  very  fertile  where  improved. 

Catskill. 

238.  Type  sample  of  the  Catskill  formation,  from  near  Mt.  Savage. 
Good  strong  land  for  grass  and  wheat.  Has  a  characteristiCy 
dark  red  color, 

Oriskany. 
290.  Type  sample  of  Orishany  from  the  follo%oing  localities: 
226  and  227,  from  near  Cumberland,  and  228,  from  Hancock.  The 
formation  is  not  very  uniform  in  texture.  The  localities 
visited  have  rather  a  fine  textured  soil,  naturally  poor  but 
capable  of  some  improvement.  The  formation  occurs  only  in 
narrow  belts  capping  hills  and  mountains,  and  is  not  of  much 
extent  in  the  State. 


276  maryland  agricultural 

Chemung,  Hamilton,  Niagara  and  Clinton. 
^89.  Type  sample  from  the  following  localities : 

234.  Subsoil  of  the  Hamilton  shale,  from  near  Mt.  Savage.     I^atur- 

allj  very  poor  but  capable  of  some  improvement  as  it  has  good 
body. 

235.  Hamilton   shale,  from   Cumberland.     Poor   lands — mostly  thin 

mountain  pastures. 
236  and  237,  Chemung  from  two  localities  near  Mt.  Savage.     Nat- 
urally rather  poor  land. 

239.  Niagara  from  near  Cumberland.     Poor  but  has  good  body  and 

is  capable  of  some  improvement. 

240.  Clinton  shale  from  near  Cumberland.     Lands  naturally  poor  but 

have  good  body. 

These  formations  appear  so  much  alike  in  texture  and  agricultural 
features  that  they  are  all  included  in  the  one  type.  They  are  nearly 
all  hill  and  mountain  pastures,  naturally  poor  and  not  capable  of 
great  improvement,  except  as  garden  spots  and  at  great  expense. 
The  soil  or  rather  subsoil,  for  there  is  little  or  no  difference,  is  a  very 
fine  grained,  powdery  material,  filled  with  small  fragments  of  the 
original  rock. 

YI.  Mechanical  Analysis  of  the  Type  Soils. 

The  soils  of  these  type  formations  differ  so  much  in  texture  that 
the  difference  is  quite  apparent  to  the  eye.  Some  are  coarser  than 
others,  the  grains  are  larger  and  there  are  fewer  of  them  in  a  given 
weight  of  soil.  The  first  thing  done,  in  the  examination  of  the 
soil,  was  to  make  a  mechanical  analysis  by  separating  the  grains 
into  groups,  according  to  size.  The  approximate  number  of  grains 
in  each  group  was  then  calculated  and  this  shows  how  much 
the  empty  space  in  the  soil  has  been  divided  up  and,  relatively,  how 
fast  water  will  move  through  the  different  soils. 

For  the  greatest  accuracy,  the  grains  should  be  separated  into  a 
large  number  of  groups,  so  that  all  the  grains  in  each  group  shall 
be  very  nearly  of  the  same  size,  but  the  analysis  takes  so  long  that 
we  have  used  only  eight  groups.  The  separations  were  made  sub- 
stantially after  Johnson  and  Osborn's  "beaker  method."  We  have 
taken  ,0001  mm.  as  the  lowest  limit  of  size  of  the  grains  of  clay, 
based   on  many  measurements  we  have  made.     The  clay  group  has 


EXPERIMENT    STATION.  277 

relatively  wide  limits  (.005-.0001  mm.)  but  we  have  not  attempted  a 
further  separation  than  this.  A  millimeter  (1  mm.)  is  equivalent  to 
about  1-25 th  of  an  inch,  so  that  the  smallest  grains  of  clay  are  about 
1-25400  inch  or  .0000039  inch  in  diameter. 

Table  4,  gives  the  results  of  the  mechanical  analysis  of  the  type 
samples  of  the  subsoils  of  the  five  formations  in  Southern  Maryland. 
The  analyses  and  calculations  based  on  the  other  type  samples  will 
not  be  completed  in  time  for  this  report."^  The  subsoils  have  been 
taken  up  first,  as  the  texture  of  the  subsoil  is  more  important  in 
determining  the  nature  of  the  land  and  its  relation  to  the  water 
supply  of  crops  than  that  of  the  soil  itself. 

Table  4: — Mechanical  Analyses  of  Type  Subsoils. 


276. 

284. 

286. 

280. 

278. 

Diameter. 
mm. 

Conventional 
names. 

Pine 
barrens. 

Truck. 

Tobacco. 

Wheat. 

River 
terrace 

2-1 

Gravel 

tl.87 

0.6« 

1.36 

0.00 

1.60 

1-.5 

Coarse  sand 

9.15 

2.89 

2.13 

0.42 

1.51 

.5-. 25 

Medium  sand 

38.37 

21.85 

7.78 

1.81 

4.15 

. 25- . 1 

Fine  sand 

33.28 

25.82 

16.57 

8.59 

4.84 

.1-.05 

Very  fine  sand 

3.52 

18.38 

19.83 

32.06 

8.54 

.05-. 01 

Silt. 

3.47 

9.48 

25.41 

23.65 

44.92 

.01-. 005 

Fine  silt 

1.55 

3.37 

4.52 

6.77 

5.78 

.005-. 0001 

Clay 

3.75 

15.30 

17.95 

22.55 

25.85 

97.96 

97.77 

95.55 

95.85 

97.19 

Organic  matter,  water,  loss. . 

2.01 

2.23 

4.45 

4.15 

2.81 

tThis  includes  1.81  per  cent,  larger  than  2mm.  in  diameter. 
Note. — Each  of  these  type  samples  is  made  up  of  samples  from  a  number  of 
localities  in  each  soil  formation. 

The  results  in  this  table  are  confusing  from  the  mass  of  figures, 
and  from  the  fact  that  each  group  has  to  be  given  a  special  value, 
depending  upon  the  size  of  the  soil  grains  which  it  contains ;  a  per 
cent,  of  clay  having  far  more  value  than  an  equal  amount  of 
gravel.  From  this  table  alone  it  would  be  difficult  to  judge  of  the 
texture  of  the  soils. 

YII.  Approximate  Number  of  Grains  per  Gram  of  Soil. 
From  the  results  in  Table  4  we  have  calculated  the  approximate 
number  of  grains  of  sand  and  clay  in  one  gram  of  the  subsoils,  as 
■■■■This  matter  has  since  been  completed  and  will  be  given  in  an  appendix. 


278 


MARYLAND    AGKICULTUEAL 


given  in  Table  5.  These  figures  are,  of  course,  onl)'  approximate  and 
the  numbers  are  far  beyond  our  comj)rehension.  Thej  may  be  used 
relatively,  however,  in  comparing  one  soil  with  another. 


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o 

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o 

M 

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o 

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o 

p 

CO 

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N 

C/J 

f^ 

O 

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M 

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U> 

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00 

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T) 

^3 

C 

^ 

cS 

■      c 

cS 

cc 

V 

OJ 

a 

C 

;i5      o 


o     a 


EXPERIMENT    STATION.  279 

It  will  be  remembered  that  the  texture  of  the  soil  is  determined  by 
the  size  and,  therefore,  by  the  number  of  grains  per  unit  weight  or 
volume  of  soil.  In  this  table  it  will  be  seen  that  the  number  of 
grains  in  the  fine  "silt"  and  "clay"  groups  so  far  exceed  the  number 
in  all  the  other  groups  combined,  that  they,  and  especially  the  clay, 
actually  determine  the  extent  of  subdivision  of  the  empty  space  in 
the  soil.  The  other  groups  may  be  neglected,  for  practically,  the 
effect  of  the  gravel  and  sand,  is  only  to  diminish  the  amount  of  clay 
per  unit  weight  or  volume  of  soil.  The  amount  of  clay  is,  therefore, 
a  very  important  factor  in  any  soil  as  it  practically  determines  the 
subdivision  of  the  empty  space  and  the  texture  of  the  land. 

Table  6 : — Total  I^umber  of  Grains  in  One  Gram. 

{Summary  of  Results  in   Table  5.) 

276 Pine  barrens *(2)  1692  000  000 

284 Truck ,.  .  .  (8)  6  868  000  000 

286 Tobacco (9)  8  258  000  000 

280 Wheat (14)  10  358  000  000 

278 River  terrace (5)  11  684  000  000 

Limestone  (grass  land). . .  (1)  24  653  000  000 

*  Number  of  localities  represented. 

The  summary  of  the  results  in  Table  6  places  the  soils  at  once  in 
their  true  agricultural  relation.  It  suggests  also  a  method  for  the 
classification  of  soils. 

From  the  mechanical  analysis  of  the  samples  which  were  used  to 
make  np  these  type  samples,  and  perhaps  of  a  large  number  of 
other  soils  of  known  agricultural  value,  it  should  be  possible  to 
determine  the  smallest  and  the  largest  number  of  grains  per  gram 
of  soil  where  these  different  crops  could  be  successfully  grown.  For 
example,  no  crop  can.  be  successfully  grown,  except  under  highly 
artificial  conditions  of  manuring  with  organic  matter,  or  by  irriga- 
tion, on  a  soil  having  so  few  as  07ie  thousand  seven  hundred  million 
grains  per  gram.  Good  m.arket  truck  is  grown  on  a  soil  having  six 
thousand  eight  hundred  million  grains.  Now  what  is  the  limit 
between  these  two  figures  where  the  soil  becomes  too  light  for  market 
truck?  Good  wheat  is  grown  on  a  soil  having  ten  thousand  millioii 
grains  per  gram,  and  this  must  be  near  the  limit  of  profitable  wheat 


280  MARYLAND   AGRICULTURAL 

production,  for  eight  thousand  'million  grains  per  gram  gives  a  soil 
rather  too  light  for  wheat,  but  well  suited  to  tobacco.  A  soil  having 
ten  thousand  million  grains  per  gram  is  too  light  for  grass,  which 
thrives  on  a  limestone  soil  having  twenty-four  thousand  million. 
Our  type  soils  should,  therefore,  sliow  the  range  for  the  profitable 
production  of  a  given  crop.  We  should  be  able  also  from  the 
mechanical  analysis  of  an  unknown  soil  to  give  it  its  true  agricultural 
place  by  reference  to  these  established  soil  types. 

It  is  not  to  be  inferred  from  these  statements  that  wheat  cannot  be 
grown  on  a  soil  having  so  few  as  one  thousand  million  grains  per 
gram.  This  number  represents  merely  the  skeleton,  or  frame- 
work, of  the  soil.  As  we  shall  see  later,  this  may  be  so  filled  in 
and  modified  by  organic  matter  as  to  enable  it  to  support  a  good 
wheat  crop,  but  at  such  an  expense  as  to  put  it  far  outside  the  limit 
of  profitable  culture.  This  is  a  matter  of  judgment  and  experience. 
The  soil  types  give  only  the  skeleton  structure  of  the  soil. 

Nor  is  it  to  be  inferred  that  wheat  may  be  grown  on  all  soils  having 
ten  thousand  m^illion  grains  or  more  per  gram  with  equal  success,  for 
the  relation  of  these  soils  to  water,  upon  which  the  cropping  depends, 
is  a  matter  not  only  of  how  much  the  space  within  the  soil  is  subdivided, 
that  is,  how  many  grains  there  are,  but  depends  also  upon  the  way 
these  grains  are  arranged.  We  will  develop  this  idea  further,  when 
we  come  to  speak  of  the  cause  of  the  deterioration  of  lands  and  of 
their  improvement. 

YII.  Approximate  Extent  or  Surface  Area  per  Cubic  Foot  of  Soil. 

We  are  able,  from  the  foregoing  i^esults,  based  on  the  mechanical 
anlysis  of  the  soils,  to  calculate  the  approximate  extent  of  surface 
area  of  the  grains  of  clay  and  sand  in  a  given  weight  or  volume  of 
soil. 

A  solid  block  of  granite,  one  foot  square  and  one  foot  high,  would 
have  six  square  feet  of  surface  area,  but  when  this  cube  of  solid  rock 
disintegrates,  forming  or  leaving  a  cubic  foot  of  soil,  half  of  the  rock 
is  dissolved  and  carried  off  and  wliat  remains  is  split  up  into  a  vast 
number  of  separate  grains  of  sand  and  clay.  If  a  soil  were  made  U2> 
of  fragments  as  large  as  this  cubic  foot  of  rock,  then,  even  if  the 
proper  water  supply  could  be  maintained  in  the  soil,  it  would  be 
impossible  for  our  staple  crops  to  get  their  needed  food  supply. 
The  soil  moisture  and  the  roots  themselves  can  only  dissolve  food 


EXPERIMENT    STATION. 


281. 


material  from  the  surface  of  the  rock.  The  rock  is  exceedinglj 
insoluble  and  the  amount  of  plant  food  which  could  be  dissolved  and 
extracted  from  six  square  feet  of  surface  by  water  or  roots,  would  be 
exceedingly  small  and  entirely  insufficient  for  the  needs  of  any  of  our 
staple  crops. 

The  soil,  however,  resulting  from  the  disintegration  of  such  a  rock 
has  an  enormous  extent  of  surface  area  if  all  the  surface  on  the 
separate  grains  of  sand  and  clay  be  considered.  Table  7  gives  the 
approximate  extent,  in  square  centimeters,  of  the  surface  area  in  one 
gram  of  our  type  subsoils  and  of  a  limestone  subsoil  from  Frederick 
Yalley.  Table  8  shows  the  approximate  number  of  square  feet  of 
surface  area  in  one  ciibic  foot  of  soil. 

Table  7: — Surface  Area  {sq.  cm.)  per  Gram  of  Subsoil. 

276.  284.        286.         280.       279 


Diameter.    Conventional 


mm. 
2-1 
1-.5. 
.5-.25 
.25-.1 

.1-.05 
.05-.01 


names. 
Gravel 
Coarse  sand 
Medium  sand 
Fine  sand 
Very  fine  sand 
Silt 


.01-.005    Fine  silt 
.005-.0001   Clay 


Pine 
barrens. 

0.5 

2.8 
23.6 
43.9 
10.8 
26.7 
47.7 
339.8 


Truck.    Tobacco.   Wheat. 


0.1 

1.0 

13.5 

34.1 

56.7 

73.1 

104.1 

1387.0 


0.2 

0.7 

4.9 

22.4 

62.5 

200.7 

142.8 


0.0 
0.1 

1.1 

11.6 
100.9 
186.2 
213.2 


River 
terrace 

0.2 

0.5 

2.6 

6.4 

26.5 

348.7 

179.5 


1668.0     2089  0     2360.0 


Limestone, 

0.0 

0.0 

0.1 

0.4 

7.6 

221.3 

344.  a 

5000.0 


495.8         1669.6       2102.2     2602.1     2924.4       5573.7 


Table  8 : — Square  Feet  of  Sprface  per  Cubic  Foot  of  Subsoil. 


276    .... 

Pine  barrens. . . . 

23  940 

square  feet. 

284 

Truck 

74  130 

11          II 

286 

Tobacco.   

84  850 

11 

280   .... 

Wheat 

94  540 

.. 

278 

Eiver  terrace .... 

106  200 

11                  u 

(2.3  acres.) 

Limestone 

202  600' 
(158  OOC 

square  feet. 
)  aeres.) 

S82  MARYLAND  AGRICULTURAL 

It  will  be  seen  that  there  are  upwards  of  24,000  square  feet  of  sur- 
face area  in  a  cubic  foot  of  the  subsoil  of  the  pine  barrens,  no  less 
tlian  100,000  square  feet,  or  2.3  acres,  of  surface  area  in  a  cubic  foot 
of  the  subsoil  of  the  river  terrace,  and  158,000  square  feet  of  sur- 
face area  in  a  cubic  foot  of  the  limestone  subsoil. 

These  figures  seem  vast,  but  they  are  probably  below,  i-ather  than 
above,  the  true  values  on  account  of  the  wide  range  of  the  diameters 
of  the  clay  group,  as  given  in  the  table.  This  gives  an  enormous 
area  for  the  roots  and  soil  moisture  to  act  on  for  the  extraction  of 
plant  food  from  the  mineral  elements  of  the  soil.  Instead  of  the  few 
square  feet  offered  by  the  cube  of  granite,  there  are  now  several 
acres  of  surface  area,  for  the  roots  to  range  over,  in  search  of  food 
and  for  the  water  to  act  on,  in  a  single  cubic  foot  of  soil.  This  great 
extent  of  surface  and  of  surface  attraction,  which  has  been  described 
as  potential  in  Section  II.,  gives  the  soil  great  power  to  absorb  moist- 
ure from  the  air,  and  to  absorb  and  liold  back  mineral  matters  from 
solution.  A  smooth  surface  of  glass  will  attract  and  hold,  by  this  sur- 
face attraction,  an  appreciable  amount  of  moisture  from  the  surround- 
ing air.  A  cubic  foot  of  soil,  having  100,000  square  feet  of  surface, 
should  be  able  to  attract  and  hold  a  considerable  amount  of  moisture 
from  the  air. 

When  a  soil  is  only  slightly  moistened  with  water  there  will  be 
nearly  as  much  exposed  water-surface  as  the  surface  of  the  soil  grains 
themselves.  The  amount  of  energy  or  tension  on  such  an  extent  of 
water-surface  will  be  very  great  and  it  is  this  which  enables  a  soil  to 
draw  up  the  large  amount  of  water  needed  by  the  crop. 

In  all  of  these  relations,  the  extent  of  surface  gives  the  soil  a  cer- 
tain strength  and  value  which  must  have  an  important  bearing  on 
crop  production  and  distribution. 

IX.  The  Circulation  of  Water  in  these  Type  Soils. 

We  have  showm  that  the  number  of  grains  per  gram,  places  these 
type  soils  in  their  true  agricultural  relation.  We  have  now  to  show 
the  reason  fdr  this  in  the  difference  in  their  relation  to  the  circulation 
of  water,  and  the  ease  with  which  a  definite  quantity  of  water  can  be 
supplied  to  a  given  crop. 

We  will  assume  that  the  grains  in  all  the  soils  have  the  same  mean 
arrangement,  then  the  relative  rate  of  circulation,  other  things  being 
equal,  will  depend  upon  how  much  space  there  is  in  the  soil  and 
upon  how  much  this  space  is  subdivided. 


EXPERIMENT    STATION.  283 

For  the  reasons  which  have  ah'eady  been  given,  we  have  not  been 
able  to  determine  the  amount  of  space  in  the  soils  which  were  used 
to  make  up  the  type  samples.  The  determinations  require  much 
time  and  great  care  to  remove  a  definite  volume  of  soil  from  the  field, 
and  this  must  be  made  the  subject  of  some  future  investigation. 
From  our  work  in  South  Carolina  on  similar  soils,  which  has  been 
referred  to,  we  have  assumed  the  per  cent,  of  empty  space  in  each  of 
the  soil  types,  given  in  the  following  tables.  These  values,  therefore, 
are  not  exact  determinations,  but  are  thought  to  be  approximately 
correct.  It  is  important  to  observe  that  the  coarser  soils  have  less 
space  and,  consequently,  when  this  space  is  completely  filled  with 
water,  the  sandy  soils  will  contain  less  water  than  the  clay  soils.  In 
a  cubic  foot  of  the  sandy  soils  there  is  considerably  less  than  half  a 
cubic  foot  of  empty  space;  in  the  same  volume  of  the  clay  soils  there 
is  over  half  a  cubic  foot  of  space  for  water  to  move  in.  This 
difference  in  the  amount  of  space  in  the  different  soils,  gives  rise  to 
an  important  modification  of  the  relative  rate  of  circulation,  when 
the  soils  are  saturated,  and  when  they  are  short  of  saturation. 

The  empty  space  in  agricultural  soils  is  hardly  ever  completely 
filled  with  water.  The  most  favorable  amount  of  water  in  the  soil, 
for  growing  plants,  as  Hellriegel  and  others  have  shown,  is  from  30 
to  50  per  cent,  of  the  water-holding  capacity  of  tlie  soil.  As  a  light 
sandy  land  has  less  space  and  will  hold  less  water  than  a  clay  soil,  the 
most  favorable  amount  of  water  for  vegetation  will  be  less  than  in  a 
clay  soil.  We  have  repeatedly  found  in  actual  determinations,  less 
water  in  light  lands  than  in  heavy  clay  soils,  and  it  is  a  matter  of 
observation  and  experience  that  light  lands  are  drier  than  heavy  clay 
soils. 

The  reason  for  this  follows  from  the  fact  that  water  circulates 
more  freely  in  these  light  soils,  by  reason  of  the  fewer  grains  and  the 
less  amount  of  subdivision  of  the  empty  space,  and  after  a  moderate 
rain  the  water  passes  down  more  readily  into  the  lower  depths  of 
the  subsoil. 

After  the  excess  of  rainfall  has  passed  down  through  the  soils  and, 
equilibruim  is  established,  there  will  be  less  water  in  the  light  lands 
than  in  the  clay  soils.  If,  then,  a  definite  quantity  of  water  is 
required,  by  the  crop  in  a  given  time,  it  can  move  up  to  the  plant 
through  the  sandy  soil  more  readily,  but  there  is  less  water-surface 
in  the  light  land  to  contract,  that  is,  there  is  less  force  to  pull  the 


284  MARYLAND    AGRICULTUKAL 

water  up.  These  points  are  well  brought  out  in  the  following  calcu- 
lations of  the  relative  rate  of  circulation  of  water  in  these  type  sub- 
soils. 

If  we  assume  in  the  first  place,  that  all  the  soils  contain  the  same 
amount  of  water,  namely  12  per  cent,  (the  most  favorable  amount  in 
the  wheat  land,)  the  relative  rate  of  circulation  will  be  as  follows : 

iq'o.  Soil.  .Space.  Water-content.  Relative  time. 

27Q Pine  barrens 40  per  cent.  12  per  cent.  17 

284..  ••  Truck 45     "        "  12     "        "  43 

286 Tobacco 50     "        "  12     "        "  68 

280...  Wheat 55     "        "  12     "        "  92 

278 River  terrace..  .  .  55     "        •'  12     "        "  100 

If  it  takes  100  minutes  for  a  quantity  of  water  to  pass  down 
through  a  certain  depth  of  the  subsoil  of  the  river  terrace,  the  same 
weight  of  water  could  pass  down  through  the  subsoil  of  the  truck 
land  in  43  minutes,  and  through  the  subsoil  of  the  pine  barrens  in  17 
minutes.  It  could  not  move  up  so  readily  for  there  is  less  water  sur- 
face^ as  we  have  shown,  to  contract  and  pull  it  up  from  below. 

When  equilibrium  is  established  and  the  water  is  moving  down  with 
about  the  same  rate  in  each  of  the  subsoils,  there  will  be  about  6.5 
per  cent,  in  the  subsoil  of  the  pine  barrens,  9  per  cent,  in  the  truck 
land  and  12  per  cent,  in  the  subsoil  of  the  river  terrace,  as  follows: 

]Sfo.  Soil.                          Space.  Water-content.  Relative  time. 

27g Pine  barrens 40  per  cent.  6.6  per  cent.  102 

284-.  ••  Truck 45     "        "  9.0     "        "  102 

285..  ••         Tobacco 50     "        "  10.5     "        "  102 

280 Wheat 55     "        "  11.7     "        "  101 

278 River  terrace.  .  .  55     "        "  12.0     "        "                100 

This  would  be  about  the  relative  amount  of  water  found  in  these 
subsoils  some  time  after  rain.  When  the  subsoil  of  the  river  terrace 
contains  12  per  cent,  of  water,  that  of  the  pine  barren  would  contain 
about  6.5  per  cent.,  that  of  the  truck  land,  9  per  cent. 

The  interesting  question  suggested  above,  comes  up  here  again.  If 
the  rate  of  circulation  of  water  through  the  light  truck  land  with  9 
per  cent,  of  water  present  in  the  subsoil,  is  the  same  as  in  the  wheat 


EXPERIMENT    STATION",  ,    285 

soil  of  the  river  terrace  with  12  per  cent,  of  water,  (the  most  favor- 
able amount  for  wheat),  then  why  are  not  the  light  truck  lands  as  good 
for  wheat  as  the  other  ?  And  the  explanation  given  above  is  only 
made  clearer  through  these  tables,  that  while  gravity  acts  with  a  con- 
stant force,  xoitli  surface  tension,  to  pull  the  water  down,  surface  ten- 
sion alone  has  to  pull  the  water  up  to  the  crop  against  gravity  ',  and 
there  is  less  surface  tension,  less  contracting  power,  less  force,  to  pull 
up  a  given  weight  of  water  in  a  given  time  in  the  light  land  than  in 
the  other.  The  wheat  crop  would  suffer  on  such  a  soil  in  a  warm,  dry 
spell,  when  it  had  to  depend  on  water  being  supplied  it  from  below. 

We  have  shown  that  there  is  less  space  in  the  light  truck  land  than 
in  the  wheat  soils,  but  the  soil  grains  being  larger,  there  are  fewer  of 
them,  and  the  space  is  not  divided  up  so  much.  Eacli  separate  space 
is  larger  and,  when  the  soil  is  short  of  saturation,  the  water  moves 
faster. 

If  however  the  soils  are  fully  saturated,  the  volume  of  empty  space 
has  an  important  value  in  retarding  the  rate  of  movement.  There  is 
less  volume  of  space  in  the  light  lands,  less  water  can  be  crowded 
into  it  than  in  the  wheat  soils,  and  so,  when  the  spaces  in  the  soils  are 
fully  saturated,  the  rate  of  movement  will  be  relatively  slower  than 
in  the  wheat  soils. 

The  relative  rate  of  movement  of  water  through  these  different 
subsoils  when  all  the  space  is  filled  with  water,  will  be  as  follows : 

No.  Soil.                           Space.                      Water-content.  Relative  time. 

276-.  Pine  barrens..  40  per  cent.  20. 10  per  cent.  (Sat.)             63 

284..  Truck 45     "        "  22.41      '        "  "  120 

286..  Tobacco    .....  50     "        "  27.42     "        "          "               103 

280  •■  Wheat 55     "        "  31.55     "        "  "  92 

278..  River  terrace.  55     "        "  31.55     "        "          "               100 

If  all  the  space  is  filled  with  water,  as  assumed  in  Table  9,  the  sub- 
soils will  contain,  respectively,  25,  28,  31,  33,  and  33  pounds  of 
water  per  cubic  foot.  If  a  given  quantity  of  water  passes  down 
through  a  depth  of  saturated  subsoil  of  the  river  terrace  in  100 
minutes,  it  would  take  about  120  minutes  for  the  same  quantity  of 
water  to  go  down  through  the  same  depth  of  the  saturated  subsoil  of 
the  light  truck  land.  This  probably  explains  a  matter  of  common 
observation  and  experience,   that  crops  on  light  sandy  lands  are  more 


286  MARYLAND  AGKICULTUEAL 

injured  in  excessive  wet  seasons  than  crops  on  heavier  soils.  The 
excess  of  water  cannot  be  removed  so  fast  by  the  light  lands,  when 
saturated,  as  in  the  heavier  soils. 

There  are  other  interestinej  lines  of  thought,  and  explanations  of 
other  matters  of  common  observation  and  experience,  suggested  bj 
this  line  of  i-easoning,  which  may  be  followed  out  at  another 
time  as  the  limits  of  this  report  allow  of  only  a  concise  narrative 
account  of  the  work  and  a  very  general  statement  of  the  appli- 
cation of  the  results. 

X.  The  Improvement  of  Soils. 

When  we  consider  that  desserts  are  barren  only  from  the  lack  of 
water  and  that  where  water  is  supplied  they  become  fertile  and  pro- 
ductive as  other  lands;  and  when  we  consider  the  immense  crops 
raised  in  dry  and  arid  countries  by  irrigation  as  well  as  the  difference 
in  the  yield  of,  crops  in  our  own  state,  in  wet  and  in  dry  seasons,  and 
other  evidences  which  will  be  published  at  another  time,  we  are 
forced  to  the  conclusion  that  vegetation  is  very  largely  dependent  for 
its  developement  and  growth  upon  a  proper  water  suppl}'',  and  that 
the  whole  art  of  cultivation  and  manuring  is  based  upon  the  possible 
control  of  the  water  supply  within  the  soil. 

We  have  shown  the  principles  upon  which  this  control  is  based ;  we 
come  now  to  an  application  of  these  principles  to  the  improvement  of 
soils. 

The  agricultural  lands  of  this  state  have  generally  good  surface 
drainage.  They  have  a  small  quantity  of  organic  matter  which  is 
fairly  uniform  in  amount  in  the  soils  of  the  different  soil  formations. 
If  such  a  soil  is  shown  by  a  mechanical  analysis  to  have  not  less  than 
ten  thousand  million  grains  per  gram,  it  has  the  structure,  or  frame 
work,  for  a  good  wheat  soil  and  should  be  classed  as  such.  If  it  does 
not  produce  good  wheat  crops,  or  if  it  has  deteriorated  from  a  more 
fertile  condition,  there  may  be  some  change  in  the  structure  of  the 
soil  through  a  change  in  the  arrangement  of  the  soil  grains. 

The  case  must  be  studied  as  a  physician  considers  the  condition  of 
a  sick  person ;  a  diagnosis  must  be  made  to  determine  the  cause  of 
the  trouble.  The  symptoms  both  of  the  soil  and  of  the  crops  must 
be  carefully  studied.  If  the  soil  is  rather  close  and  too  retentive  of 
moisture,  the  plants  are  large  and  sappy  and  give  a  small  yield  of 
fruit  or  seed  in  proportion  to  the  size  of  the  plant  and  the  amount  of 


EXPERIMENT    STATION.  287 

food  material  gathered  b}'  the  plant  from  the  atmosphere  and  soil. 
The  crop  is  also  inclined  to  be  late  it  maturing. 

If  the  soil  is  dry  and  leachy,  the  plants  are  small  and  give  a  small 
yield,  but  the  yield  is  relatively  larger  in  proportion  to  the  food 
material  that  lias  been  stored  up. 

Other  symptoms,  besides  this  relation  of  the  yield  of  grain  and 
fruit  to  the  size  of  the  plant,  that  is,  to  the  amount  of  food  material 
stored  up  by  the  plant,  offer  evidence  as  to  the  condition  of  the  .soil 
and  the  changes  needed  for  its  improvement,  such  as  the  vigor  of  the 
plant,  the  way  it  develops  and  grows,  the  diseases  and  insect  ravages 
to  which  it  is  subject,  and  the  influence  of  wet  and  dry  seasons  on 
the  crop  production. 

The  cotton  crop  at  the  South  is  very  sensitive  to  these  conditions  of 
environments.  The  wheat  crop  more  readily  adapts  itself  to  the  con- 
ditions under  which  it  is  grown,  and  is,  therefore,  not  so  sensitive  or 
reliable  for  showing  up  these  soil  conditions. 

There  is  need  of  an  instrument,  or  a  method,  to  show  the  actual 
rate  with  which  water  moves  both  up  and  down  within  the  soil  in 
its  natural  position  in  the  held,  and  such  a  method  must  be  devised, 
for  the  information  is  of  great  importance. 

It  has  been  shown  how  the  relative  rate  of  circulation  of  water 
may  be  calculated  from  the  mechanical  analysis  of  the  soil.  If  this 
calculated  rate  could  be  compared  with  the  actual  rate  of  circulation 
in  the  soil  in  the  held,  it  would  indicate  the  relative  arrangement  of 
the  soil  grains,  so  that  if  we  had  such  a  method  there  would  be  no 
such  necessity  for  studying  the  symptoms  of  the  plant  to  tell  in  what 
direction,  and  how  far,  the  conditions  in  a  soil  have  departed  from 
the  typical  conditions  required  by  a  given  crop,  or  natural  to  the  soil 
formation. 

If  the  rate  of  circulation  of  water  within  the  soil  is  shown,  by 
actual  observation  or  by  its  effect  upon  plants,  to  be  slow^er  than  the 
rate  calculated  from  the  mechanical  analysis,  and  slower  than  the  rate 
of  circulation  in  the  typical  soil  for  that  crop,  the  texture  of  the  soil 
may  be  changed  by  changing  the  arrangement  of  the  soil  grains. 
The  smallest  grains  may  be  drawn  closer  to  the  larger  ones,  making 
some  of  the  spaces  larger  and  others  exceedingly  small.  Lime, 
kainite  and  phosphoric  acid  seem  to  have  this  effect,  as  their  con- 
tinued use  makes  the  soil  more  loamy,  looser  in  texture,  and  less 
retentive  of  moisture. 


288  MARYLAND    AGRICULTURAL 

Many  of  our  agricultural  lands  need  improvement  in  the  other 
direction,  they  need  to  be  made  closer  in  textnre  and  more  retentive 
of  moisture.  We  have  found  that  ammonia,  the  caustic  alkalies, 
carbonate  of  soda,  and  probably  many  other  substances,  possibly 
organic  substances  in  general,  tend  to  prevent  this  flocciilation  and  to 
push  the  smaller  grains  further  apart,  making  the  spaces  within  the 
soil  of  a  more  uniform  size  and  thus  retarding  the  rate  of  circulation 
of  the  soil  moisture.  We  cannot  say  what  practical  value  this 
will  have  in  its  application  to  agriculture  until  more  work  has  been 
done. 

When  a  solution  of  organic  matter  comes  in  contract  with  lime, 
kainite,  acid  phosphate,  and  with  certain  soils,  the  organic  matter  is 
precipitated  from  solution  in  light,  bulky  masses,  and  these  masses 
may  fill  up  the  spaces  within  the  soil  with  solid  matter  which  not 
only  retards  the  rate  of  circulation  of  water  downward  by  gravity, 
but,  by  increasing  the  extent  of  water-surface  within  the  soil,  it  also 
assists  in  pulling  water  up  from  below. 

If  so  much  organic  matter  is  added  to  the  soil  that  it  cannot  be 
curdled  or  precipitated  from  solution,  it  may  be  injurious  in  the  soil 
by  reducing  the  surface  tension  of  the  soil  moisture,  the  force  which 
draws  the  water  to  the  plant  as  needed.  The  judicious  use  of  lime, 
kainite  or  acid  phosphate,  along  with  the  organic  matter,  will  insure 
the  precipitation  of  the  organic- matter  from  solution  and  thus  give  a 
value  to  the  application  which  it  would  not  otherwise  have  had. 

This  gives  a  value  to  stable  manure,  out  of  all  proportion  to  the 
amount  of  plant  food  which  it  contains.  Lime,  also,  either  alone  or 
when  acting  with,  organic  matter,  has  a  distinct  value  for  all  classes  of 
land.  The  nitrogenous  matters  in  the  stable  manure,  and  in  other 
organic  matters,  would  determine  the  value  as  a  fertilizer,  for  it  is 
only  the  nitrogenous  compounds  which  are  so  easily  precipitated  from 
solution  by  the  mineral  matters  of  the  soil  and  of  fertilizers.  If  the 
carbohydrates,  such  as  starch,  sugar  and  woody  fibre,  could  be  as 
readily  precipitated  from  solution  in  light,  bulky  masses,  by  lime  and 
the  mineral  matters  of  the  soil,  then  sawdust  or  other  organic  refuse 
containing  little  nitrogen,  would  have  nearly  the  same  fertilizing 
value  as  the  more  expensive  nitrogenous  materials. 

The  whole  history  of  plat  experiments  shows  that  it  is  not  the  plant 
which  is  to  be  manured  for,  but  the  soil  conditions  must  be  changed 
to  produce  the  plant. 


EXPERIMENT    STATION.  289 

The  corn  plant  on  one  soil  requires  potash,  on  another  soil,  phos- 
phoric acid,  on  another  soil,  nitrogen,  and  again  on  another  soil  a  com- 
bination of  two  or  more  of  these  fertilizers.  On  the  whole,  there  is 
no  such  fertilizer  in  our  State  for  wheat  as  lime,  used  alone  or  acting 
with    organic   matter. 

Plat  experiments  frequentlj^  give  a  larger  yield  when  lime, 
salt  or  plaster  is  used,  and  even  when  nothing  at  all  has  been 
added  to  the  soil,  than  when  the  more  expensive  plant  foods 
have  been  used.  Especially  when  acid  phosphate  or  potash  has  been 
used  alone,  the  yield  is  often  smaller  than  where  nothing  has  been 
added  to  the  soil. 

Under  ordinary  conditions,  our  crops  do  not  require  special  plant 
foods,  but  they  all  have  somewhat  different  habits  of  growth  and 
development  and  can  best  gather  food  under  somewhat  different 
physical  conditions.  We  have  seen  how  these  different  fertilizing 
materials  cliange  the  physical  conditions  in  the  soil. 

This  opens  up  a  new  and  wide  field  for  investigation  in  the  study 
of  the  physical  conditions  of  the  soil  in  their  relation  to  plant  growth 
and  developement,  and  the  effect  thereon  of  the  different  fertilizers 
and  manures.  It  will  be  through  this  study  that  the  true  theory  of 
fertilization  will  be  seen,  and  an  interpretation  and  added  value  be 
given  to  the  immense  amount  of  chemical  data,  which  has  accumu- 
lated, relating  to  the  soil. 

Correction: — Through  an  oversight,  part  of  the  explanation  of  the  phenomenon 
of  flocculation  on  page  258  was  transposed.  It  should  read  as  follows  :  If  the 
potential  of  the  surface  particle  of  water  is  less  than  of  a  particle  in  the  interior  of 
the  mass  of  liquid,  there  will  be  surface  tension,  and  the  two  grains  will  come 
together  and  be  held  with  some  force,  as  their  close  contact  will  diminish  the  num- 
ber of  surface  particles  in  the  liquid.  If,  on  the  other  hand,  the  potential  of  the 
particle  on  the  surface  of  the  liquid  is  greater  than  the  potential  of  a  particle  in  the 
interior  of  the  liquid  mass,  the  surface  will  tend  to  enlarge,  and  the  grains  of  clay 
will  not  come  close  together,  as  their  close  contact  will  diminish  the  number  of 
surface  particles  in  the  liquid  around  them. 

M.  W. 


APPENDIX. 


Since  the  main  part  of  my  report  was  written,  I  have  been  able  to 
secure  the  services  of  Mr.  F.  P.  Veitch  and  Mr.  J.  B.  Latimer, 
graduates  of  the  class  of  1891  of  the  Agricultural  College.  Mr. 
Yeitch  has  completed  the  mechanical  analysis  of  our  type  subsoils, 
which  enables  me  to  present  the  results  here,  with  a  short  discussion. 

The  mechanical  analysis  of  these  type  subsoils,  given  in  Table  13, 
is  based  upon  the  "line  earth,"  or  material  smaller  than  2  ')mn.  in 


290 


MARYLAND    AGRICULTURAL 


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EXPERIMENT    STATION.'  291 

diameter.  Three  of  these  subsoils  were  not  tlioroughly  disintegrated^ 
bnt  contained  small  fragments  of  rock,  which  were  separated  out  and 
weighed,  the  remaining  line  earth  being  used  for  the  mechanical 
analysis.  The  samples  contained  the  following  per  cent,  of  coarse 
and  of  fine  material. 

290  238  289 

Oriskany.  Catskill.  Shales. 

Coarser  than  2  mm.         5.80  21.28  17.23 

"Fine  earth" 94.20  78.72  82.77 

"We  have  not,  as  yet,  attempted  to  study  the  efEect  of  these  frag- 
ments of  rock  upon  the  relation  of  the  soils  to  the  movement  of 
water,  but  have  confined  ourselves  to  the  simpler  study  of  soils  hav- 
ing no  coarse  fragments,  and  we  will,  therefore,  disregard  tliis  coarse 
material  for  the  present,  and  treat  the  soils  as  though  composed  only 
of  the  fine  earth.  It  may  well  be,  that  in  some  localities  disintegra- 
tion has  gone  further  than  where  these  samples  were  taken,  and  that 
these  same  soil  formations  there  contain  no  coarse  fragments  of  the 
undecomposed  mck.     Our  results  should  apply  directly  to  such  a  soil. 


1  692  000  000 
6  868  000  000 

8  258  000  000 

9  154  000  000 
10  358  000  000 
11684  000  000 
14  736  000  000 
14  839  000  000 

18  295  000  000 

19  638  000  000 

24  653  000  000 

Table  11  gives  the  approximate  number  of  grains  of  sand  and  clay 
in  one  gram  of  these  type  subsoils,  and  the  results  conlirm  what  has 
been  stated  before,  that  the  soils  thus  arranged  are  in  the  order  of 
their  relative  agricultural  value. 


Table  U: 

— Approximate  Number 

Subsoil. 

276. 

Pine  barrens. 

284. 

Truck. 

286. 

Tobacco. 

290. 

Oriskany. 

280. 

Wheat. 

278. 

River  terrace. 

282. 

Triassic  red  sandstone. 

238. 

Catskill. 

289. 

Shales  (Hamilton,  &c.) 

288. 

Helderberg  limestone. 

.... 

Trenton  chazy  limestone, 

292  MARYLAND   AGKICULTURAL 

The  Oriskany  formation  is  of  very  small  agricultural  importance,  as 
it  has  such  a  small  area  in  the  State,  occurring  in  narrow  belts,'  the 
widest  being  hardly  more  than  a  mile  across.  It  has  a  place  in  the 
table  between  the  tobacco  and  wheat  soils  of  Southern  Maryland. 

The  Triassic  i-ed  sandstone  and  the  Catskill  formations  are  shown 
to  have  about  the  same  structure.  The  soils  themselves  are  very 
similar,  and,  except  for  their  distinct  geological  and  geographical 
positions,  they  should  be  grouped  as  a  single  soil  type.  The  Catsldll 
formation  covers  a  considerable  area  in  the  valley  between  Sideling 
Hill  and  Town  Hill  Mountains,  and  again  between  the  Great  Savage 
Mountain  and  the  Meadow  Mountain,  wath  a  very  narrow  belt  near 
Dan's  Mountain,  between  Mt.  Savage  and  Cumberland,  wdiere  our 
single  sample  of  the  formation  was  obtained.  This  is  an  important 
soil  formation,  which  should  be  more  carefully  studied,  and  of  which 
more  samples  should  be  taken.  From  the  general  appearance  of  the 
land,  as  seen  from  the  train  in  passing,  there  does  not  seem  to  be  as 
.  much  undecomposed  rock  in  the  soils  of  these  wider  areas  as  is  con- 
tained in  the  sample,  which  is  given  here.  I  should  estimate  that 
there  are  about  32i)  square  miles  of  this  Catskill  formation  in  West- 
ern Maryland,  and  about  the  same  area  of  the  Triassic  red  sandstone 
to  tlie  north  and  south  of  the  Frederick  Valley. 

The  Hamilton  and  Chemung  shales  have  their  widest  exposure 
around  Hancock  and  on  either  side  of  the  Polish  Mountain,  covering 
perhaps  1-25  square  miles.  The  Clinton  and  ^Niagara  shales  occur  in 
very  narrow  ridges,  giving  a  much  smaller  exposure  than  this.  The 
mechanical  analysis  of  the  type  sample  of  these  formations  gives 
39.36  per  cent,  of  "clay,"  or,  approximately,  eighteen  thousand  mil- 
lion grains  per  gram.  The  samples  contained  many  small  fragments 
of  rock,  so  far  disintegrated  that  they  went  to  pieces  at  once  between 
the  iingei"s,  or  when  they  were  gently  rubbed  with  the  rubber  pestle 
under  water.  As  these  fragments  would  so  readily  fall  to  pieces  in 
handling,  much  of  this  was  classed  as  "fine  earth,"  and  only  17.23 
per  cent,  could  be  separated  out  as  coarse  material.  I  think  that  this 
type  has  not  its  true  agricultural  place  in  the  arrangement  of  these 
tables,  as  the  grains  of  sand  and  clay  have  evidently  not  the  same 
arrangement  as  in  a  soil  where  the  disintegration  has  been  more  com- 
plete and  the  grains  are  more  evenly  distributed.  It  was  stated  in  a 
previous  section  tliat  these  soils  were  naturally  poor,  but  had 
good  body  and  could  be  improved.  This  table  shows  that  they 
have  good  body,  and  it  remains  now  to  show  how  the  actual 
conditions  differ  from  the  best  conditions  wdiich  should  prevail  in  this 
type  soil,  and  how  the  soils  can  best  be  improved.  In  other  States, 
where  these  shales  are  more  thoroughly  decomposed,  they  make  some 
of  the  most  fertile  lands.  They  should  have  a  value  not  far  below 
that  of  the  Helderberg  limestone. 

There  is  but  a  small  area  of  the  Helderberg  limestone  in  this  State, 
occurring  in  several  narrow  belts  crossing  Western  Maryland.     The 


EXPERIMENT    STATION.  293 

area  of  the  whole  formation  is  only  a  few  square  miles  in  extent. 
The  formation  ^ives  a  very  fine  grass  and  wheat  soil.  In  the  calcula- 
tions which  follow,  I  have  used  the  Helderberg  limestone  as  the 
strongest  soil,  and  the  best  for  grass  and  wheat  of  any  of  the  types, 
not  having  sufficient  samples  from  the  Trenton  limestone  to  establish 
a  satisfactory  type  sample. 

I  must  again  urge,  as  in  a  former  paragraph,  that  the  number  of 
grains  of  sand  and  clay  give  only  the  skeleton  structure  of  the  soil, 
and  that  this  may  be  so  filled  in  with  organic  matter  as  to  greatly 
modify  the  physical  properties  of  the  soil.  The  amount  of  organic 
matter  is  assumed  to  be  fairly  constant  for  the  different  types,  and  is  a 
matter  of  more  importance  in  the  study  of  local  soils.  It  is  important 
also  to  remember  tliat  the  structure  of  the  soil,  and  its  relation  to  the 
circulation  of  water,  is  dependent  not  only  upon  how  many  grains  there 
are  per  gram,  but  upon  how  these  grains  are  arranged.  In  our  calcu- 
lations, we  have  assumed  that  they  have  the  same  mean  arrangement 
in  all  the  type  soils ;  but  this  is  evidently  not  so  in  regard  to  local 
soils,  for  we  have  suggested  that  the  deterioration  of  soils  is  due 
largely  to  a  change  in  the  arrangement  of  the  soil  grains,  changing  the 
relation  of  the  soil  to  the  circulation  of  water.  These  type  samples, 
however,  represent  more  than  this,  for  they  are  selected  to  represent 
the  average,  natural  condition  of  these  great  soil  formations. 

The  average,  natural  arrangement  of  the  grains  in  these  great  soil 
formations  must  be  determined  to  give  an  additional  basis  of  com- 
parison between  the  different  types,  but  especially  for  the  comparison 
of  local  soils,  which  may  have  departed,  in  one  way  or  another,  from 
the  type  conditions,  through  a  re-arrangement  of  the  grains  of  sand 
and  clay.  This  is  important  in  the  study  and  classification  of  local 
soils. 

It  is  quite  possible  to  conceive  of  a  brick  clay  or  a  tight  pipe  clay, 
having  no  more  grains  per  gram  than  this  Helderberg  limestone.  If 
a  few  drops  of  caustic  ammonia  was  applied  to  the  Helderberg  soil, 
through  which  a  certain  weight  of  water  was  passing  in  a  hundred 
minutes,  the  grains  of  soil  would  be  re-arranged,  and  it  would  take 
several  thousand  minutes  for  the  same  amount  of  water  to  pass.  On 
the  other  hand,  a  little  lime  water  would  make  the  soil  more  l@amy, 
and  hasten  the  rate  of  movement  of  water.  "We  have  thus  a  loam 
soil,  a  good  clay  soil  and  an  impervious  pipe  clay,  out  of  the  same 
soil,  by  a  simple  re-arrangement  of  the  sand  and  clay.  The  arrange- 
ment of  the  grains  has,  therefore,  an  important  bearing  on  tlie  physi- 
cal properties  of  the  soil,  but  this  is  largely  dependent  upon  local 
causes,  which  modify  the  conditions  in  the  original  soil  formation. 

From  the  results  in  these  tables  it  would  seem  that  the  subsoil  of 
good  grass  land  would  have  not  less  than  30  per  cent,  of  clay,  or  al)out 
twelve  tJioiisand  million  grains  per  gram,  and  good  wheat  land  not 
less  than  twenty  per  cent.,  or  about  nine  thousand  million  grains  per 
gram ;  ])rovided^  these  grains  have  a  certain  mean  arrangement  and 


29i  MARYLAND    AGKICULTUEAL 

that  this  skeleton  structure  contains  an  average  amount  of  organic 
matter.  It  mast  be  remembered  that  if  either  the  arrangement  of 
the  grains  or  the  amount  and  condition  of  the  organic  matter  departs 
from  the  average  condition  of  the  soil,  the  plijsical  condition  of  the 
local  soil  will  depart  from  the  typical  conditions  of  the  soil  formation. 
These  type  subsoils  have  the  following  approximate  extent  of  sur- 
face area  per  cubic  foot : 

276.  Pine  barrens.  40  per  cent,  space.  23  940  square  feet. 

284.  Truck.  45  "  "  . "  74 130  "  " 

286.  Tobacco.  '  50  "  "  "  84  850  "  " 

290.  Oriskany.  50  "  "  "  87  720  "  "    * 

280.  Wheat.  55  "  "  "  94  540  "  " 

278.  Kiver  terrace.  55  "  "  ''  106  200  ''  " 

282.  Triassic.  55  "  "  "  127  000  "  " 

288.  Helderberg  limestone.  65  "  "  "  129  700  "  " 
238.  Catskill.  55  "  "  "  133  300  "  " 

289.  Shales  (Hamilton,  &c.)  60  "  "  "  142  700  "  " 

The  practical  bearing  of  these  results  has  been  quite  fully  set  forth 
in  Section  VIII.  The  Helderberg  limestone  has  a  place  here  before 
the  Catskill  and  the  shales,  because  we  have  given  it  a  high  percentage 
of  empty  space,  higher  perhaps  than  should  have  been  given.  It  has, 
of  course,  the  highest  percentage  of  surface  area  per  unit  weight  of 
any  of  these  subsoils,  but  the  larger  amount  of  space  lowers  the  per- 
centage  per  unit  volume  of  soil. 

From  the  foregoing  results,  we  have  calculated  the  relative  rate 
with  which  a  given  quantity  of  water  would  pass  through  an  equal 
depth  of  these  subsoils,  under  a  constant  force  and  with  the  same 
amount  of  water  (12  per  cent.)  in  each  subsoil,  taking  the  subsoil  of  the 
Helderbei'g  limestone  as  a  basis  of  comparison. 

It  would  appear  from  results  on  next  page  that,  with  12  per  cent,  of 
water  present  in  all  the  subsoils,  it  wall  take  only  8  minutes  for  a  quantity 
of  water  to  pass  through  the  subsoil  of  the  pine  barrens,  which  would 
require  100  minutes  to  pass  through  the  same  depth  of  the  subsoil  of 
the  Helderberg  limestone.  It  will  pass  through  the  subsoil  of  the 
wheat  land  of  the  river,  terraces  in  Southern  Maryland  in  about  49 
minutes.  It  will  move  down  more  readily  in  these  lighter  soils 
from  its  own  weight,  but,  as  I  have  urged  in  a  previous  section,  a 
given  quantity  of  water  could  not  be  raised  so  readily  to  supply  the 
needs  of  a  growing  crop,  for  there  would  be  less  exposed  water-surface 
to  contract,  that  is,  there  would  be  less  force  to  pull  it  up. 


EXPERIMENT    STATION. 


295 


No. 

Soil. 

Space 

Water-content. 

Relative 
Time. 

276. 

Pine  barrens. 

40] 

3er 

cent. 

12 

3er 

cent. 

8 

284. 

Truck. 

45 

12 

21 

286. 

Tobacco. 

50 

12 

33 

290. 

Oriskany. 

50 

12 

35 

280. 

Wheat. 

55 

12 

45 

278. 

Kiver  terrace.- 

55 

12 

49 

282. 

Triassic. 

55 

12 

56 

238. 

Catskilk 

55 

12 

58 

289. 

Shales  (Hamilton, 

&c.) 

60 

12 

81 

288. 

Helderberg  limestone. 

65 

a 

12 

100 

I  liave  calculated  the  amount  of  water  which  should  be  present 
in  these  different  subsoils  for  the  rate  of  movement,  due  to  a  con- 
stant force,  to  be  the  same  as  in  the  subsoil  of  the  Helderberg 
limestone,  containing  12  per  cent,  of  water. 


No. 

Soil. 

Space. 

Water-content. 

Relative 
Time. 

276. 

Pine  barrens. 

40 

per 

cent. 

5.3 

per 

cent. 

101 

284. 

Truck. 

45 

7.2 

101 

286. 

Tobacco. 

50 

8.4 

102    . 

290. 

Oriskany. 

50 

8.6 

101 

280. 

Wheat. 

55 

9.4 

100 

278. 

River  terrace. 

55 

9.6 

100 

282. 

Triassic. 

55 

10.0 

101 

238. 

Catskill. 

55 

10.1 

100 

289. 

Shales  (Plamilton, 

&c.) 

60 

11.2 

100 

288. 

Helderberg  limestone. 

65 

12.0 

100 

The  relation  of  these  different  subsoils  to  water  is  as  different  as  in 
the  artificial  conditions  in  green  house  culture.  The  difference  is 
amply  sufficient  to  account  for  the  distribution  of  plants  and  for  the 
known  relations  of  these  different  soils  to  plant  growth  and  develop- 
ment. 

I  have  also  calculated  the  relative  rate  with  which  water  would 
move,  under  a  constant  force,  through  these  different  subsoils,  if  all 
the  space  within  them  was  filled  with  water. 


296  MARYLAND    AGKICULTUEAL    EXPEKIMENT    STATION. 


Relative 

No. 

Soil. 

Space. 

Water- 

content. 

Time. 

276. 

Pine  barrens. 

40  per  cent. 

20.10  per 

cent,  (sat.) 

74     • 

284. 

Truck. 

45     "       " 

22.41     " 

" 

141 

286. 

Tobacco. 

50     "       " 

27.42     " 

" 

121 

290. 

Oriskany. 

50-    "       " 

27.42     " 

" 

130 

280. 

Wheat. 

55      "       " 

31.55     " 

" 

109 

278. 

River  terrace. 

55     "       " 

31.55     " 

" 

119 

282. 

Triassic. 

55     "       " 

31.55     " 

" 

137 

238. 

Catskill. 

55     "       '< 

31.55     " 

" 

140 

289. 

Shales  (Hami 

Iton. 

,  &c.) 

60     "       " 

36.14     " 

" 

123 

288. 

Helderberg  li 

mestone. 

65     "       " 

41.22     " 

u 

100 

It  will  be  seen  that  the  amount  of  space  assigned  to  these  different 
soil  formations,  has  an  important  bearing  on  the  relative  rate  with 
which  water  will  move  within  the  different  soils.  The  coarser  text- 
ured soils  have  less  space  and  will  contain  less  water  than  the  clay 
soils.  The  subsoil  of  the  truck  land  has  only  45  per  cent,  of  space, 
and  will  hold  but  22.41  per  cent,  by  weight  of  water,  when  this  space 
is  completely  filled.  The  subsoil  of  the  Helderberg  limestone  has  65 
per  cent,  of  space,  and  will  hold  41.22  per  cent,  by  weight  of  water, 
or  nearly  twice  as  much  as  the  truck  land.  When  the  soils  con- 
tained only  12  per  cent,  of  water,  a  quantity  of  water  would 
move  through  the  truck  land  in  21  minutes,  which  would  require 
100  minutes  to  pass  through  the  subsoil  of  the  Helderberg  lime- 
stone. When,  however,  these  soils  are  taxed  to  their  utmost, 
it  will  take  141  minutes  for  a  quantity  of  water  to  pass  through  the 
truck  land,  which  would  go  through  the  limestone  subsoil  in  100 
minutes.  As  suggested  in  a  previous  section,  this  undoubtedly  ex- 
plains a  matter  of  common  observation  and  experience,  that  crops  on 
these  light  lands  are  more  injured  by  excessive  wet  seasons  than  crops 
on  heavier  soils. 

These  calculations  of  the  relative  rate  with  which  water  will  move 
within  these  different  subsoils,  are  based  solely  upon  the  skeleton 
structure.  The  influence  of  the  organic  matter  is  not  considered,  and 
the  soil  grains  are  assumed  to  have  the  same  mean  arrangement. 
These  two  factors,  the  amount  of  organic  matter  and  the  arrange- 
ment of  the  soil  grains,  are  probably  nearly  alike  under  the  normal 
conditions  which  prevail  in  these  great  soil  formations ;  but  if  they 
have  not  relatively  the  same  effect  in  the  different  soils,  they  will 
undoubtedly  make  the  difference  in  the  relation  of  these  soils  to  the 
circulation  of  water,  still  wider  than  the  values  we  have  assigned. 
Each  of  these  factors  requires  a  distinct  line  of  investigation,  and  this 
is  necessary  to  the  practical  use  and  application  of  this  work. 


I.IBRA.IIY    of 

iMiassaciiiiset' 

OCT  22 1910 

A-grioTilt-arsu 

THE    SOIL,  o°^-s« 


CONSIDERED  AS  A 


SEPARATE  AND  DISTINCT  DEPARTMENT  OF  NATURE, 


ROBERT.  SEER ELL.W 00  0, 


Corresponding  Member  of  the  National  Institute. 


WASHINGTON,   MARCH,   1850. 


The  most  palpable  source  of  nutrition  to  all  created  beings  was  sup- 
posed by  the  ancients  to  possess  the  attributes  of  vitality ;  it  was  there- 
fore an  amiable  weakness  on  their  part  to  personify  the  Earth,  and  to 
hold  her  in  pecaliar  veneration.  Modern  science  has  banished  this  beau- 
tiful sentiment  from  its  stern  philosophy,  but  it  can  never  invalidate  the 
fact  that  there  are  certain  ingredients  of  the  soil  (whatever  be  their 
origin)  which  claim  intermediate  rank  between  matter  in  such  states  of 
combination  as  the  chemist  can  produce  by  synthesis,  and  the  lowest 
specimens  of  vegetable  organisms  :  neither  has  it  yet  successfully  proved 
that  the  same  elements  in  other  shape  than  the  organic  salts  of  humus 
contribute  with  equal  efficiency  to  the  luxuriance  of  vegetation,  although 
there  is  evidence  in  volclmic  and  other  localities  to  show,  that  an  excess 
of  either  free  carbonic  acid  gas,  or  ammonia,  or  water,  even  when  the 
other  minerals  present  suffice  for  the  wants  of  plants,  is  injurious  to  the 
highest  degree.  A  greater  proportion  than  at  present  of  those  gases  and 
vapours  in  the  atmosphere,  and  consequently  in  the  soil,  may  have  favored 
the  earliest  denizens  of  our  globe  :  those  tribes  have  now  nearly  passed 
away,  or  their  constitution  has  been  modified  with  modifications  of  cli- 
mate, &c. 

A  just  appreciation  of  fossil  organic  remains  has  elicited  a  probable 
trulh,  that  function  and  organization  proceed  through  both  kingdoms  of 
nature  by  parallel  lines  of  advancement,  observable  since  the  different 
periods  of  the  world  at  which  they  respectively  commenced  their  exist- 
ence. It  would  seem  as  if  some  general  law,  harmonizing  with  the 
earth's  progress  in  its  physical  Capacity,  governed  the  succession  of  these 
products,  an  idea  which  is  further  supported  by  their  gradual  develop- 
ment at  the  present  day  from  the  germinal  to  a  perfect  state.  We  should 
also  bear  in  mind  the  remarkable  fact,  that  animals  and  vegetables  are 
blended  together  so  as  to  render  any  attempt  to  define  their  distinguish- 


^  /^n 


2 

ing  properties  utterly  futile.  Vegeto-animals  have  been  fully  recognised 
by  naturalists ;  and  we  are  next  led  to  inquire  whether  the  soil,  forming 
a  connection  between  organized  and  unorganized  matter,  partakes  of  a 
vegeto-minerdl  character  in  the  highest  acceptation  of  the  term. 

The  animal  department,  although  indebted  for  its  growth  and  prime 
condition  to  azotized  aliment  approximating  more  or  less  in  its  nature 
the  tissues  themselves,  borrows,  from  vegetables  especially,  hydro-car- 
bonaceous substances  of  a  less  complex  composition,  a  portion  of  which 
is  converted  into  fat,  another  portion  is  directly  oxidized  and  excreted, 
while  a  third  is  presumed,  in  the  case  of  the  lowest  animals,  to  be  con- 
vertible by  means  of  ammonia  into  gelatine,  &c.,  their  integuments  cor- 
responding with  those  of  plants  as  surfaces  absorbent  of  nourishment, 
sufficiently  at  least  to  establish  a  close  relation  between  both  races  in 
this  respect  as  well  as  in  their  both  inhaling  oxygen.*  Again,  the  vege- 
table department  in  its  highest  range,  although  dependant  upon  rich 
mould  or  organic  manures  for  its  most  efficient  support,  (as  man  and 
some  other  animals  are  upon  flesh,)  draws  from  the  atmosphere  elements 
convertible  into  cellulose,  &c.,  indicating  the  claims  of  animals  upon 
vegetables,  of  vegetables  upon  the  soil,  and,  as  I  shall  endeavor  to  show, 
the  ultimate  dependance  of  the  soil  upon  the  atmosphere.  Nature  evi- 
dently proposes  more  than  one  resource  for  the  maintenance  of  her  crea- 
tures ;  and  unity  of  design,  which  pervades  the  works  of  creation,  would 
suggest  that,  although  the  soil  receives  its  most  unequivocal  accessions 
from  the  debris  of  plants,  it  nevertheless  allows  the  crude  materials  of 
air  to  circulate  within  its  pores,  and  to  form  more  notable  combinations. 
Animals,  vegetables,  and  the  soil  are  constituted  in  large  proportion  of 
particles,  which  have  possessed,  but  which  no  longer  retain,  the  usual 
characteristics  of  life — particles,  be  it  observed,  which  threaten  to  resolve 
themselves  into  simpler  forms,  unless  the  tendency  to  .disintegration  be 

*The  oxidation  of  the  hydrocarburets  is  generally  believed  to  liberate  calorie  in  living  bodies  as 
a  primary  result,  but  I  respecifullv  maintain  that  it,  in  the  first  instance,  causes  the  surrender  of 
electricity  which  w^as  previously  combined  ;  heat  consequently  bigjomes  a  secondary  effect  of  an 
altered  consistency  or  composition  in  solids  or  fluids,  whereby  their  specific  capacity  for  caloric 
is  aflfected.  The  temperature  of  animals  is  exaggerated  by  physical  exertion,  which  causes  the 
contraction  of  muscles  and  a  more  rapid  circulation  of  the  blood.  A  large  portion  of  their  food  is 
already  combined  with  oxygen  in  the  proponion  to  form  water ;  no  heat  is  therefore  evolved  from 
this  source,  and  the  separation  of  free  water  from  their  surfaces  in  the  shape  of  vapour  produces  a 
reduction  of  temperature  perhaps  equivalent  to  the  heat  generated  by  the  conversion  of  venous  into 
arterial  blood.  The  slow  reactions  between  highly  constituted  substances  may  be  identical  in  a 
chemical  point  of  view  with  ordinary  cases  of  combusti.m,  but  the  results  very  difl^erent ;  the 
amount  of  heat  liberated  being  proportionate  to  the  greater  or  less  competency  of  conducting 
media  to  carry  off  the  electricity  set  free,  or  of  other  contiguous  molecules  in  the  circulation  or 
elsewhere  to  appropriate  that  imponderable  by  forming  new  combinations.  And  here  I  may  be 
permitted  to  add,  that  if  the  solution  of  a  simple  metal  in  the  voltaic  apparatus  liberates  a  force 
which,  on  being  conducted  by  a  special  arrangement  of  wire  around  an  enclosed  bar  of  iron,  mag- 
netizes it,  a  fortiori  the  resolution  of  more  complex  particles,  such  as  those  contained  in  the  ani- 
mal circulation,  might  be  supposed  capable  of  contracting  (magnetizing)  a  muscle  enclosed  with- 
in a  network  of  conducting  nervous  filaments.  A  ganglion  is  the  voltaic  apparatus^  certain  con- 
stituents of  the  blood  electrolytes,  the  motor  and  sensitive  nerves  conducting  media,  and  the  mus- 
cle, which  is  insulated  by  cellular  matter  and  ligament,  a  magnet.  The  contr.action  of  a  muscle 
or  a  congeries  of  muscles  would  not  necessarily  diminish  the  volume  of  their  mass,  because  their  re- 
duction of  size  only  tends  to  enlarge  the  capacity  of  the  surrounding  cellular  substance  ;  free  in- 
gress is  therefore  allowe  d  to  the  blood  between  the  fibres,  and  cmisequently  greater  efficiency 
produced  in  the  parts. 


3 

counteracted  by  a  force  of  an  opposite  kind.  The  soil  possesses  no  evi- 
dence of  organization  either  in  mass  or  in  detail ;  but  organization  may 
mark  grades  of  development  without  being  indispensable  to  characterize 
living  matter.  Nothing  can  be  more  indefinite  than  even  the  essential 
properties  of  life.  Can  physiologists  determine  at  what  precise  moment 
the  vital  principle  is  surrendered  by  a  piece  of  muscle  cut  from  the  leg 
of  a  healthy  animal  ?  The  separation  of  a  part  merely  shortens  its  term 
of  existence  by  destroying  perhaps  the  faculty  of  self-preservation  or  re- 
production. Where  then  shall  we  find  the  first  link  in  the  self-supporting 
chain  of  vital  products?  Are  we  to  consider  the  vesicles  or  cells  which 
the  microscope  discovers  almost  everywhere  on  the  earth's  surface  as  ex- 
hibiting the  simplest  manifestations  of  life,  or  may  we  refer  its  rudiments 
to  the  corpuscles  of  blood,  or  to  certain  constituents  of  sap  ? 

I  propose  to-  regard  the  soil  as  a  creature  sui  generis,  sustaining 
living  bodies  whilst  it  is  itself  sustained  by  them.  Its  proportions  are 
limited  by  the  means  of  increment  placed  at  its  disposal.  If  the 
natural  history  of  soil  be  studied,  we  find  that  although  it  may  in- 
crease enormously  under  certain  conditions,  and  although  its  term  of 
maturity  may  be  prolonged  to  an  apparently  indefinite  extent,  its  ulti- 
mate dissolution,  in  whole  or  in  part,  is  a  matter  of  as  much  certainty 
as  the  lapse  of  ages.  Organized  bodies,  however,  display  their  power 
of  increase  more  particularly  in  their  progeny,  which  represent  the  pa- 
rent in  an  enlarged  individuality.  The  soil,  likewise  constituted,  as  I 
shall  presently  endeavor  to  show,  of  many  individuals  of  different  char- 
acter, is  capable  of  propagating  its  kind  by  a  quasi-fissiparous  process — 
that  is  to  say,  a  portion  of  veritable  mould  being  isolated  from  the  main 
body  and  placed  in  a  favorable  situation,  exerts  a  quickening  influence 
upon  surrounding  matter  of  elemental  identity:  mould,  consequently, 
either  enlarges  in  bulk  itself,  or  gives  bulk  to  vegetables,  just  as  vegeta- 
bles, during  their  growth,  either  enlarge  in  bulk  themselvs,  or  give  bulk 
to  animals  which  feed  upon  them.  It  may  be  further  urged,  as  a  gene- 
ral proposition,  that  animals,  plants,  and  the  soil,  increase  and  multijsly 
in  co-ordinate  ratios,  and  that,  with  the  continued  addition  of  light,  a 
much  greater  mass  of  matter  will  be  engaged  in  the  enjoyment  of  more 
exalted  faculties,  either  in  an  organized  or  semi-organized  shape. 

Aboriginal  soil,  then,  may  be  attributed  to  the  rays  of  the  sun  co-ope- 
rating with  physical  changes  of  certain  universally  diffused  substances, 
which  I  shall  presently  mention — changes  of  form,  consistency,  and  po- 
sition, capable  of  impressing  the  heterogeneous  residue  with  new  affini- 
ties. We,  however,  regard,  as  chiejiy  instrumental,  at  the  present  day, 
in  the  generation  of  humus  de  novo  from  carbonic  acid  and  water,  the 
forces  liberated  by  already  existing  humus,  or  by  materials  of  higher 
grade  in  the  act  of  decomposition — forces  identical  with  those  emitted 
from  the  luminous  worlds  around  us. 

Commencing  with  the  lowest  grade  of  progressive  developments,  we 
submit  for  consideration  :  first,  whether  ulmin  and  other  semi-organized 
substances  were  not  originally,  and  are  not  still, produced  from  carbonic 
acid  and  water  at  the  expense  of  ammonia  which  becomes  decom- 
posed in  the  ground  by  means  of  oxygen,  nitrogen  being  liberated  upon 
the  same  terms  which  vegetables  prescribe  for  themselves  during  an  an- 


alogous  process  of  transformation.*  Secondly,  whether  the  disintegra- 
tion of  those  hydrocarburets  which  are  formed  in  vegetables  from  ulmin, 
such  as  starch,  gums,  oils,  &c.,  does  not  promote  the  formation  of  various 
azotized  proximate  principles,  when  ammonia,  sulphur,  phosphorus,  and 
some  few  other  minerals,  are  present.  Lastly,  whether  tl^e  dissolution 
of  these  proteine  and  allied  compounds  into  less  complex  forms,  or  into 
their  ultimate  elements,  does  not  generate  cellulose,  &c.  The  idea  on 
which  we  particularly  insist  is,  the  reluctance  on  the  part  of  bodies, 
whether  organized  or  unorganized,  to  allow  their  constitutional  forces  to 
exhaust  themselves  by  their  component  materials  becoming  resolved 
into  simpler  combinations,  as  long  as  contiguous  matter  evinces  the  dis- 
position of  assuming  an  identical  character  or  an  equivalent  complexi- 
ty of  constitution.  For  this  reason,  the  same  forces  which  enter  into 
the  constitution  of  vegetables  are  apparently  transmitted  from  one  gene- 
ration to  another.  But,  on  the  other  hand,  it  |nust  be  confessed  that^ 
were  it  not  for  the  incessant  appropriations  of  the  luminous  element  by 
the  surface  materials  of  our  globe,  no  further  progress  in  the  quantity 
or  quality  of  chemico-vital  phenomena  could  be  anticipated. 

It  would  likewise  be  unreasonable  to  expect  the  occurrence  of  these 
spontaneous  formations  of  soil,  where  the  want  of  indispensable  pre- 
requisites prohibits  what  would  be  an  ordinary  train  of  events  in  more 
favored  regions.  The  fixed  alkalies  and  -a-lkaleidg,  in  moderate  quantity, 
might  expedite  the  process,  and  yet  the  same  bases,  or  ammonia,  or 
water,  in  excess,  effectually  prevent  it.  To  consider  them  as  tending 
to  break  up,  under  all  circumstances,  rather  than  to  superinduce  more 
complex  relations  of  matter,  would  be  to  adopt  an  error  equivalent  with 
considering  oxygen  an  element  of  universal  destruction. 

Viewed  solely  as  an  accumulation  of  dead  or  effete  materials,  the 
ground  presents  a  melancholy  picture  of  desolation,  but  as  a  thing  of 
life  it  ofiers  eminent  support  to  the  doctrine  of  development.  As  soon 
as  a  fit  habitation  was  prepared  for  land-animals  and  plants,  they  each 
in  the  fulness  of  time  entered  on  their  career.  There  is  an  aptitude  in 
this  arrangement,  and  no  less  probable  is  it  that  the  first  and  simplest 
forms  of  living  matter  derived  their  forces  from  existing  substances  of 
lower  degree  in  complexity,  and  that  the  light  of  heaven  co-operated 
then,  as  it  does  now,  in  the  glorious  consummation.  Water-plants  flour- 
ished long  before  dry  land  appeared ;  these  must  have  subsisted  upon 
gases  and  salts  dissolved  in  the  ocean,  and  their  debris  became  the  source 
of  much  primeval  soil.  This  admission  by  no  means  militates  against 
the  proposition  that  semi-organized  compounds,  constituting  humus,  may 
also  be  formed  in  Nature's  laborator}''  by  a  direct  union  of  the  elements 
concerned,  the  most  obvious  cause  of  a  primary  character  being  the 
redaction  of  ammonia,  or  its  transformation,  into  water  and  nitrogen, 
by  means  of  oxygen.  Whether  other  compounds  be  formed  in  the  soil, 
such  as  nitrates,  which  are  due  to  progressive  as  well  as  retrograde  re- 

*  It  may  be  observed  that  the  gaseous  effluvia  (excretions  proper)  respired  by  the  leaves  of 
plants,  are  for  the  most  part  simple  elements,  as  oxygen  and  nitrosren,  which,  on  assuminsr  the 
aeritorm  condition,  give  up  the  electricity  previously  binding  them  with  solids  in  t*ie closest  chemi- 
cal relations ;  their  ioes  of  ibis  force  redounds  to  the  benefit  of  plants  by  the  consequent  fixation 

of  <^arhon. 


t 

actions,  must  depend  upon  dynamic  contingencies.  Holding  these  pre- 
mises in  mind,  we  are  led  to  inquire  whether  the  decomposition  of  semi- 
organized  compounds  did  not  liberate  the  necessary  forces  and  introduce 
the  lowest  types  of  vegetable  organisms,  under  conditions  of  the  world 
more  favorable  than  at  present,  and  w^hich  we  can  scarcely  now  appre- 
ciate.* These  in  turn  becoming  decomposed,  and  surrendering  their 
forces,  may  have  forwarded  new  combinations  of  vegetable  matter,  until 
we  reach  a  period  of  the  earth's  history  teeming  with  vital  phenomena 
familiar  to  us. 

Germs,  like  nuclei  of  lesser  note,  may  be  identical,  or  nearly  so,  in 
their  ultimate  or  proximate  elem.ents,  and  j-et  differ  in  the  proportions 
of  their  combined  imponderables.  On  this  hypothesis  the  variety  of 
vegetables  and  even  animals  is  divested  somewhat  of  mystery  ;  the  ele- 
ments of  nutrition  being  the  same,  the  congenital  forces  which  direct 
the  earliest  vital  movements  in  each  particular  genus  or  species  deter- 
mine their  subsequent  figure  and  organization. 

Af  er  making  due  allowance  for  climate  and  the  immediate  effects  of 
solar  irradiation  upon  the  digestive  powers  of  plants,  we  attach  no  little 
importance  to  the  shape  in  which  their  food  is  presented  to  the  roots.  It 
is  asserted  by  the  modern  school  of  Agricultural  Chemists,  that  the  or- 
ganic food  of  plants  is  exclusively  carbonic  acid  and  ammonia  dissolved 
in  water,  and,  of  course,  the  force  of  life  is  esteemed  the  chief  cause  of 
all  organic  changes  of  a  progressive  character.  With  us,  on  the  con- 
trary, it  is  contended,  that  the  substances  aforesaid  could  not  possibly  be 
metamorphosed  into  higher  compounds  except  by  the  addition  of  light, 
or  of  forces  identical  with  light,  derived  from  organized  and  semi-orga- 
nized materiel  in  the  act  of  decomposition.  It  is  well  known,  that  no 
manure  is  more  acceptableto  vegetables  than  their  own  decaying  leaves, 
or  the  ciebris  of  a  higher  class  of  plants;  the  explanation  now  offered 
for  this  fact  by  authors  entil  led  to  our  utmost  respect,  is,  as  stated  above, 
very  sample  ;  but  unfbriunately  it  leaves  the  solution  of  ulterior  pheno- 
mena hopeless.  To  attribute  the  more  abstruse  transmutations  to  a  force 
of  life  is  tantamount  to  an  abandonment  of  principles  applicable  to  all 

*  These  conditions  have  reference  to  termer  bipolar  niuvements  of  our  eirth,  not  of  an  extra- 
vagant, but  of  an  exaggerated  kind.  1  intend,  on  some  future  occ-asi  m,  lo  submit  reasons  for  the 
belief  tiiiit  the  sun  is  the  imtiiei  iate  cause  of  the  diurnal  rotation  of  planets  within  the  solar  sys- 
tem, and  of  their  annual  changes  of  position  and  presentation  To  be  more  explicit :  if  solar 
rays  be  conipnund'-d,  ;is  I  shall  araiie,  of  repellent  and  aitiactive  forces  neutralized  by  their  com- 
bination ill  light,  and  they  be  decomposed  on  the  surface  "f  the  ear  h,  (tins  surface  being  a  nnxt-d 
one  of  soliils,  liquids,  and  aeriform  fluids  )  we  can  understand  how  more  of  the  calorific  rays  may 
be  delaiiif-d  on  the  peripheral  or  outer  portion  of  oui  planet,  and  exert  an  influence  there,  while 
the  eleciric  rays,  for  the  most  pari,  pass  on  to  ihe  innermost  surtai:e  of  the  soliil  crust,  causing  ad- 
ditional layers  to  be  precipitated  from  the  central  fluid  mass.  A  tempo  ary  loss  of  equilibrium 
thus  occasioned  hrtween  the  opposite  sides  of  the  sphere,  produces  a  cenirifusial  tendency  in  the 
comparatively  enlarged  proximal  surface,  and  a  centripetal  tendency  in  the  d  stal  surface,  which 
becomes,  each  section  of  it  for  the  instant,  comparatively  smaller  than  its  antipod.  We  further 
surmise  that  the  earth  has  reached  its  present  rate  of  movement  and  fxtent  of  bipolar  osoillatioii 
after  considerable  diminution  id  intensity  in  the  North  ;iiid  Soutu  hemispheres  respectively,  at 
different  epochs  ;  that  the  approaches  to  a  more  perlect  Hqnilibrium^and  conse'quent  alterations  of 
climate  from  ihis  cause^have  been  so  gradual  within  the  historic  period  as  to  have  escaped  the  no- 
lice  of  observers  in  tins  hrlJ  of  science.  I  am  not  acquainted  with  any  more  plausible  explanation 
of  the  undoubted  changes  of  level  in  the  ocean  s-ince  the  commencement  of  the  ternary  era,  as  evi- 
denced by  phenomena  cf  universal  extent. 


6 

physical  changes  for  the  production  of  which  chemists  are  unable  to  con- 
trol or  concentrate  the  usual  forces  of  matter. 

Practical  agriculturists  will  ke«irf?adi^g>>^i™Q^vi?fe<g;ycria^^ 

that  proximate  principles  must  be,  and  in  all  cases  are,  reduced 
before  they  can  be  absorbed  by  the  roots.  Because  analytical  chfmists 
are  unabje  to  dissolve  by  artificial  means  divers  ingredients  of  humus, 
it  does  not  follow  that  a  force  derived  from  the  voltaic  movements  of 
contiguous  living  tissues  is  incompetent  to  do  so;  neither  does  it  follow 
that  the  constituents  of  the  ascending  sap  vessels,  or  of  animal  chylife- 
rous  ducts,  represent  matter  in  its  identical  form  as  appropriated  from 
the  prim®  viae,  or  the  soil,  because  the  organic  portions  of  food  may 
become  attached  to  the  presenting  superficial  tissues,  before  the  force  of 
absorption  separates  and  reduces  them  to  other  soluble  ccmpounds  as 
found  in  the  sap  and  chylous  lymph.  Although  1  have  contended  ihat 
the  precipitation  of  the  solids  in  living  bodies  is  mainly  due  to  forces 
derived  from  analogous  materials,  yet  accretions  to  the  roots  of  plants 
probably  occur  at  all  seasons  ;  during  spring  and  summer,  however,  the 
foliage  enjoys  the  privilege  of  appropriating  aeriform  ibod  by  means  of 
light,  in  addition  to  the  forces  borrowed  from  chemical  and  mechanical 
reactions. 

The  usual  articles  of  food  correspond  more  or  less  with  the  tissues 
which  prevail  in  living  bodies;  hence  it  happens  that,  when  referring  to 
animals,  practical  as  well  as  speculative  agriculturists  lay  great"  stress 
upon  fibrin,  albumen,  phosphate  of  lime,  &c.;  when  referring  to  plants 
they  formerly  paid  especial  regard  to  the  ordinary  ingredients  of  humus, 
and  while  pursuing  that  natural  system  (apart  from  the  use  of  highly 
stimulating  manures,  both  organic  and  inorganic)  were  not  troubled 
with  the  treatment  or  the  discussion  of  modern  vegetable  diseases.  We 
now  suspect  that  just  as  there  are  peculiar  principles  in  vegetables  which 
produce  constitutional  effects  on  animals,  so  there  are  in  vegetable  mould 
of  good  quality  combinations,  not  the  result  merely  of  decomposition,  but 
of  direct  union  between  the  elements  concerned;  and  that  these  vegeto- 
mineraL varieties  are  of  great  importance,  and  define  the  nicer  qualifi- 
cations of  soil  and  consequent  character  of  plants  cultivated  therein. 
The  nervous  matter  of  animals  taken  as  food  appears  most  likely  to 
sustain  the  nervous  system  and  to  promote  the  growth  of  neurine  within 
our  own  frames.  No  people  feeding  on  vegetables  exclusively  has  ever 
attained  eminence  in  the  scale  of  nations  ;  not  because  neurine  cannot 
be  formed  from  vegetable  products,  but  because  it  cannot  be  so  bounti- 
fulljr  formed.  However  much  disposed  the  digestive  apparatus  may  be 
to  reduce  the  ingesta  to  a  homogeneous  fluid,  certain  substances  pass  its 
ordeal  which  may  eventually  give  flavor,  color,  and  other  characteristics 
to  both  animals  and  vegetables.*  Public  opinion  has  changed  even  in 
respect  to  the  elements  which  necessarily  enter  into  the  composition  of 

*A  very  general  repugnance  to  truik  raised  upon  night-soil  exists,  and  I  believe  the  objections 
are  to  a  certain  extent  valid.  When  vegetables  are  supplied  with  but  a  moderate  amount  of  such 
offensive  manure,  the  probability  is,  that  the  digestive  powers  of  the  roots  will  completely  alter  the 
character  of  such  portions  of  food  as  are  not  assimilated  by  the  soil  ;  or  even  if  any  is  direcily 
absorbed  into  the  vegetable  system,  it  is  very  rapidly  decomposed  and  passed  away.  The  case  is 
different  when  plants  are  rendered  rank  and  stimulated  by  an  excess  of  sewage;  and  it  is  from 
such  an  unnatural  and  continuous  process  of  forcing  growth  that  we  instinctively  revolt. 


vegetables,  but  is  still  adverse  to  an  ackriowledgeitient  of  any  advaii* 
tage  derivable  from  the  direct  absorption  of  compounds  highly  endowed* 
We  cannot  detect  any  absolute  contrast  in  kind,  such  as  is  alleged  to 
exist,  between  the  materials  constituting  the  food  of  animals  and  vege- 
tables, but  simply  a  difference  in  amount  of  semi-organized  and  mine- 
ral nutriment  appropriated  by  the  races  respectively,  corresponding  with, 
their  functions  and  the  complexity  of  their  organisms.  The  fungous  and 
certain  parasitic  tribes  establish  this  view  of  the  subject  almost  conclu- 
sively. Light  is  necessary  to  their  health  and  welfare  in  different  de- 
grees ;  its  influence  upon  the  functions  of  the  human  body  being  small, 
there  is  the  greater  necessity  for  man's  securing  a  full  supply  of  protein- 
ized  aliment,  and  a  moderate  allowance  of  those  vegetable  stimulants 
and  beverages  which  administer  to  his  gratification.  It  is  in  vain  to 
shut  our  eyes  to  what  some  may  consider  a  humiliatory  fact,  that  diet 
essentially  contributes  to  our  physical  and  mental  calibre. 

From  these  miscellaneous  data  we  infer  that,  although  humus  con- 
sists mainly  of  well-known  organic  matter,  it  contains  other  substances 
which  perform  an  office  entirely  overlooked  by  agriculturists,  and  ad- 
monishes them  to  reconsider  the  necessity  of  frequent  rotations  in  crops, 
so  far  as  permanent  improvement  of  the  soil,  and  not  immediate  profit 
by  overtaxing  its  every  capability,  is  concerned.  The  staples  of  a  coun- 
try, being  ascertained  by  experience,  may  be  encouraged  by  strictly  res- 
toring to  the  ground  the  refuse  of  those  staples  as  specific  manure.  The 
minute  products  referred  to  exhibit  to  my  mind  degrees  of  chemico- vital 
complexity  and  corresponding  differences  in  their  physiological  relations. 
Not  the  least  reason,  perhaps,  why  the  cerealia  in  particular  are  disin- 
clined to  extreme  climates,  or  certain  regions  of  country  in  even  temperate 
latitudes,  is  the  same  which  prevented  them  from  sooner  gracing  the  bosom 
of  our  earth,  to  wir,  the  want  or  insufficiency  of  appropriate  semi-organ- 
ized aliment.  I  may  be  told  that  grain  has  been  successfully  raised  with- 
out the  least  portion  of  humus,  or  any  of  this  highly-extolled  materia  ali- 
mentaria.  We  will  join  issue  on  this  point,  and  await  the  verdict  of  good 
and  true  men.  who  will  we'gh  the  evidence  of  unexceptionable  and  long- 
continued  experiments;  and  if  the  cerealia  do  not  degenerate  or  become 
diseased,  as  potatoes  have  become,  by  the  injudicious  refinements  of  art, 
I  shall  be  agreeably  disappointed.  There  cannot,  I  suspect,  be  too  great  a 
supply  of  mould  if  there  be  also  a  proper  proportion  of  mineral  ingre- 
dients, and  silica  in  particular,  to  support  the  luxuriant  stem.  While 
calculating  the  value  of  this  class  of  plants  we  should  be  mindful  not 
to  underrate  the  straw,  whether  as  food,  litter,  or  manure,  for  domestic 
consumption.  The  tuber  of  potatoes  has  been  perhaps  over-stimulated 
by  unfermented  organic  manures  not  possessing  a  sufficiency  of  mineral 
bases  to  ensure  hardy  germs,-  whereas,  what  seems  to  threaten  wheat  is 
an  excess  of  inorganic  elements  over  the  organic,  so  as  to  render 
it  eventually  more  grain  than  stem  ;  and  thus  by  forcing  year  after  year 
exuberant  seed  and  a  precocious  progeny,  we  endanger  the  permanent 
welfare  of  the  plant.  It  is  true  that  the  grain  crops  are  not  cultivated 
for  their  leaves  or  roots,  as  cabbages  or  turnips  are,-  but  does  not  the 
constitution  of  the  germ  depend  upon  the  efficiency  of  the  parent's  whole 
structure  ?  The  evil  is  analegous  to  that  of  breeding  in  and  in,  whereby 


certain  organs,  peculiar  products,  and  morbid  tendencies  are  exaggera* 
ted  to  the  prejudice  of  the  other  parts  and  functions.  Such  a  system 
must  terminate  disastrously  to  animals  and  vegetables,  as  it  operates 
injuriously  to  the  healthy  condition  and  growth  of  humus,  when  by  re" 
pea'ed  over-doses  of  any  one  element,  or  by  the  total  neglect  of  others, 
or  by  allowing  certain  noxious  elements  to  accumulate,  we  depress  the 
productive  energies  of  the  soil. 

An  argument  is  frequently  raised  in  disparagement  of  mould,  that  an 
excess  of  vegetable  matter,  as  in  swamps  or  heath-moors,  is  unfavor- 
able to  a  wholesome  vegetation  :  on  the  other  hand,  experiments  have 
proved  that  certain  plants  will  thrive  in  pure  charcoal — plants  which  do 
not  deserve  to  be  styled  useful  except  by  indirection^  transplanted  from 
rich  garden  earth,  containing  abundant  resources  in  their  systems,  sup- 
plied freely  with  M^ater  perhaps  saturated  with  organic  matter,  in  a 
close  atmosphere  charged  with  concentrated  nutriment,  in  a  green-house 
which  collec'^s  the  rays  of  the  sun  with  great  effect  upon  growth  ;  plants 
such  as  these,  many  of  which  cannot  survive  a  sudden  change  of  tem^ 
perature,  and  die  out  or  are  forgotten  in  a  few  generations,  are  brought 
in  comparison  wi'h  field  crops,  t  e  support  of  man  and  his  fortunes! 
It  may  not  he,  inappropriate,  by  way  of  comparison,  to  direct  my  readers 
to  those  conditions  of  society  in  which  a  pampered  aristocracy  is  found 
in  juxta-posiiion  with  a  degraded,  ignorant,  and  vicious  populace :  the 
former-are  the  hot-house  plants,  the  latter  those  noisome  weeds  which 
from  their  very  ranknesS  are  cumbersome  to  the  ground.  Happy  is 
that  country  in  w'lich  neither  class  exists,  but  a  population  of  intelligent 
freemen,  with  such  qualifications  of  mind  and  body  as  ennoblethe  race. 

As  tar  as  plants  administer  to  the  food  of  men  and  domestic  animals, 
their  importance  may  be  graduated  by  the  amount  of  their  fecula,  gum, 
oils,  &c.,  or  of  albumen,  &c.  In  order  to  obtain  these  products  tl<e  plants 
are  generally  destroyed,  some  of  them  in  embryo  as  seeds  and  tubers, 
some  more  advanced  in  life  :  but  we  never  wait  until  these  latter  sponta- 
neously cease  to  live,  because  at  the  period  of  their  natural  dissolution 
the  r  hyd -o-carbonaceous deposites  have  been  converted  into  lignin.  The 
pro'einized  deposi'es  in  the  cells  and  nitrogenous  solutions  in  the  sap 
have  also  disappeared ;  they  have  done  their  appropriate  duty,  which 
par'ly  corresponds  with  that  performed  by  the  adipose  deposites  in  the 
cellular  substance  of  animals,  or  by  the  fatty  matters  of  bile.  Vegeta- 
bles, with  a  view  to  their  self-preservation,  are  known  to  use  the  hydro- 
carbonaceous  substances  in  their  sap  for  building  up  their  structures,  at  the 
same  time  borrowing,  as  I  conceive,  the  necessary  forces  from  the  azotic 
ingredients,  un  il  the  germs  divert  the  juices  measurably  from  the  stem 
and  branches.  In  consideration  of  the  collateral  uses  oi'azotized  matter  in 
vegetables  we  are  too  apt  to  regard  it  as  forming  an  integral  portion 
of  a  plant  per  se.  The  vegetable  and  vegeto-mineral  kingdoms  economize 
nitrogen,  not  for  its  own  sake,  but  for  the  advantageous  reactions  which 
it  promotes:  the  vege  o-animal  and  animal  kingdoms  appropriate  hydro- 
carburets  chiefly  for  that  purpose.  The  same  principle-may  be  extended 
to  their  modes  of  growth  at  the  incipient  stage  of  their  existence  ;  phane- 
rogamous flowei'ing  plants  not  being  fecundated  until  the  pollen  reaches 
the  blossom,  nor  the  animal  ovum  until  the  semen  masculinum  quickens  it. 


The  very  compound  ammonia  which  under  favorable  circumstances,  such 
as  an  abundance  of  carbonaceous  aliment,  might  forward  the  growth  of 
plants,  under  other  circumstances  becomes  the  means  of  disintegrating 
their  frame- work  even  unto  utter  debility  and  death.  It  is  for  this  reason  I 
deprecate  an  excessive  use  of,  or  an  entire  dependence  upon,  the  fertilizing 
salts  now  so  prevalent,  which  will  probably  cause  a  more  rapid  ex- 
haustion of  the  soil  unless  we  keep  oar  farm§  in  good  heart ;  and  then 
we  may  lay  on  the  minerals  with  a  liberal  hand.  Thus  are  true  econ- 
omy and  high  tillage  combined.  Our  interest  demands  that  we  foster  the 
carbonaceous  elements  of  the  soil  on  the  Atlantic  slope  of  this  conti- 
nent, in  order  to  compete  with  the  middle  States  of  the  West,  notwith- 
standing the  diseases  of  new  countries  which  affect  both  animals  and 
vegetables:  nearly  all  of  them  will  soon  be  avoided  by  scientific  and 
careful  husbandry,  more  particularly  by  draining.  The  refuse  of  our 
homesteads  and  green  manures  must  be  our  chief  resource,  and  in  pro-' 
portion  as  we  gain  carbon  by  any  available  means,  we  should  encourage 
its  still  further  accumulation  by  an  equivalent  admixture  of  mineral 
bases,  among  which  ammonia  is  pre-eminently  serviceable,  both  as  a 
solvent  or  vehicle,  and  as  a  stimulant  in  the  manner  suggested. 

In  reply  to  those  who  consider  the  atmosphere  competent  to  supply  a 
full  amount  of  carbon  both  to  the  leaves  and  roots  of  our  field  and  gar- 
den crops,  and  who,  conformably  with  this  doctrine,  rely  upon  mineral 
manures,  I  would  ask  why  the  ammonia  which  is  furnished  in  the  same 
way  does  not  suffice.  Can  the  vapor  of  water  dissolved  in  air,  or  even  the 
dew  which  is  deposited  at  night,  sustain  under  ordinary  circumstances 
the  welfare  of  the  higher  class  of  vegetables  for  a  season,  not  to  mention 
a  series  of  years  ?  It  might  as  well  be  contended  that  no  rain  is  needed 
anywhere,  because  in  Egypt  the  periodical  overflow  of  the  Nile  ren- 
ders it  unnecessary  there  by  soaking  the  adjacent  plains  to  an  extra- 
ordinary depth,  as  that  wheat  can  be  raised  on  poor  soil  for  many 
successive  years  without  the  slightest  artificial  or  natural  additions  of 
carbon  in  some  of  its  solid  or  liquid  forms. 

We  do  not  propose  adding  compounds  of  nitrogen  to  worn-out  soil 
solely  for  the  purpose  of  raising  vegetable  mould,  although  the 
improvement  in  the  soil  is  the  first  step  in  the  improvement  of 
our  vegetables,  and  consequently  of  our  animals.  Whether  our  in- 
crease of  wealth  consist  of  azotized  food  which  has  been  acquired  at 
the  expense  of  hydro-carbonaceous  matter  in  vegetables,  or  whether  it 
consists  of  hydro-carbonaceous  organizable  matter  in  the  soil  which  has 
been  acquired  at  the  expense  of  ammoniacal  ingredients,  the  chemical 
process  is  identical ;  and  when  the  value  of  good  mould  is  taken  into 
account,  the  diflerence  betw^een  the  market  prices  of  the  organized  and 
semi-organized  products  is  not  always  in  favor  of  the  first. 

During  the  decomposition  of  a  manure  heap  or  a  compost  bed,  as  long 
as  ammoniacal  fumes  escape,  provided  the  air  be  allowed  to  percolate  the 
mass,  and  there  be  no  deficiency  of  fixed  alkalies  and  alkaline  earths,  I 
fully  believe  that  a  positive  addition  of  semi-organized  substances  results; 
although  the  retention  of  ammonia  is  doubly  desirable  far  direct  ap- 
propriation by  growing  plants,  a  desideratum,  which  may  be  in  some 
measure  effected  bv  artificial  means.     Were,  however,  the  loss  of  am- 


10 

monia  complete,  which  it  generally  is  not,  the  porous  character  of  the 
new-born  mould  would  attract  back  again  a  certain  proportion.  Thus 
it  happens  that  as  in  the  atmosphere,  carbonic  acid,  ammonia,  and  vapor, 
hold  a  proportionate  relation  to  each  other,  so  do  they  in  the  soil  near 
the  surface  of  the  ground,  and  it  is  in  consequence  of  the  natural  ina- 
bility of  the  mineral  bases  to  regulate  their  oMm  movements  satisfacto- 
rily in  reference  to  vegetation,  that  man  is  called  upon  to  remedy  any 
defects  or  excesses.  It  is  usually  asserted  by  those  who  admit  the 
sapply  of  carbonic  acid  and  ammonia  to  the  roots  from  decaying  organ- 
ic matter,  that  the  atmosphere  was  the  primeval  source  of  those  elements; 
they  therefore  refer  the  origin  of  vegetables  or  vegetable  growth  to  that 
A^ast  magazine,  as  amply  empowered  to  sustain  what  it  originated.  We 
admit  the  joint  influence  of  gases,  liquids,  and  solids  on  living  bodies,  and 
this  we  hold  to  be  suflicient  to  account  for  all  the  material  phenomena 
and  reactions  of  life. 

Whether  this  theory  be  right  or  wrong,  no  injury  can  accrue  from  the 
adoption  of  a  practice  founded  on  its  requirements.  We  should  by  no 
means  place  our  sole  reliance  upon  the  natural  but  slow  formations  of 
soil  as  food  for  our  cultivated  crops,  any  more  than  we  should  rely  upon 
the  organic  elements  of  the  atmosphere,  or  of  the  same  elements  absorb- 
ed by  ground  kept  in  fine  tilih.  For  precisely  similar  reasons  we  should 
object  to  feeding  our  domestic  animals  upon  food  slightly  azotized,  if  our 
aim  be  to  gain  flesh  and  nerve.  Under  favorable  conditions  then,  and 
by  the  aid  of  light,  the  pulverized  surface  of  worn-out  soil  becomes  slow- 
ly self-renovated,  provided  its  texture  be  porous  and  yet  sufficiently  re- 
tentive; and  this  recuperation  proceeds  the  more  rapidly  in  proportion 
to  the  amount  of  semi-organized  substances  already  existing.  A  nucleus 
assists,  without  being  necessary  to,  formative  action.  We  may  not  at 
first,  or  at  once,  attain  a  pabulum  adapted  to  sweet  vegetation  ;  indeed 
Ave  might  never  succ'eed  without  slight  extraneous  additions.  I  therefore 
do  not  recommend  any  purely  natural  sj^stem  of  agriculture  for  civi- 
lized communities;  but  as  a  question  of  physiolog}^  I  contend,  that 
as  a  coarse  vegetation  precedes  the  development  of  nobler  plants, 
so  the  commonest  earthy  bases,  in  conjunction  with  water  and  the 
elements  of  the  atmosphere,  serve  to  prepare  poor  land  for  future 
usefulness,  by  a  succession  of  higher  and  higher  subterranean  products; 
and  among  the  elements  of  air  I  include  phosphorus,  sulphur,  and  some 
other  minerals,  either  in  solution  or  mechanically  suspended. 

It  is,  moreover,  questionable,  whether  the  organfic  acids  in  combination 
with  mineral  bases,  or  oth er  still  more  abundant  ga^emcKS^Bibefca^s^i^aai  con- 
stituents proper  of  soil,  are  so  unstable  as  generally  supposed  ;  a  doubt 
which  may  be  extended  to  the  constituents  proper  of  living  vegetables  and 
animals,  as  long  as  easily-decomposable  matters^in  the  circulation  or  other- 
wise favorably  located,  are  available  for  functional  purposes;  whether, 
for  instance,  the  exposure  of  those  hydrocarburets  to  the  atmosphere,  by 
repeated  fallows,  necessarily  entails  their  speedy  loss  in  the  absence  or 
comparative  paucity  of  growing  plants  ;  the  latter  alternative,  of  course, 
resulting  in  no  necessary  loss,  provided  the  plants  be  allowed  to  rot  on 
the  ground  or  within  the  furrow.  My  own  impression  is,  that  under  the 
circumstances  stated,  and  as  long  as  mdisture  is  maintained,  partial  de- 


11 

^f^d-jfr^''**^    .ai^M^6.«>.*<lf   ^jr^-^i^OK.  ^e*.,.^^^--^^ 

composition  is  adequately  compensated  by  ^ao^^Kaiaj^segteaiJZ^J^^EQi^^ 
^wne,  these  again  to  be  supplanted  in  natural  order  by  original  hydrocar- 
bonaceous  deposites  at  the  expense  of  the  atm,osphere.  Uncropped  land 
which  has  been  kept  constantly  worked  for  several  successive  seasons, 
or  which  has  been  lying  waste  for  five  or  ten  years,  may  be  gradually 
accumulating  vegeto-mineral  products  peculiar  to  the  climate,  to  such 
an  extent  that  the  application  of  a  little  guano  alone  will  ensure  a  re- 
munerating crop  of  grain.  This  is  no  argument  in  disproof  of  my  main 
position,  for  I  have  uniformly  discovered  that,  where  the  ground  was  de- 
cidedly worthless  and  bare,  the  whole  class  of  mineral  manures  disap- 
pointed me ;  but  where  a  scanty  allowance  of  humus  gave  them  a  chance 
of  turning  that  pittance  to  immediate  account,  the  crop  spoke  for  itself, 
if  the  season  was  favorable ;  although,  as  I  have  before  remarked,  it 
was  tasking  the  ground  to  its  utmost  strength  for  the  purpose  of  giving  . 
the  crop  a  good  start. 

The  constitutional  depravity  of  the  middle  regions  in  Maryland  and 
Virginia  must  be  assigned  to  the  exhaustion  of  available  alkalies 
and  alkaline  earths,  and  to  the  too  rapid  withdrawal  of  sulphur  and 
phosphorus.  Let  the  proper  mineral  bases  bear  the  right  proportion  in 
a  raw  surface  composed  of  rock  lately  disintegrated,  and  if  the  climate 
be  genial,  there  can  be  little  doubt  of  a  soil-formation,  and  subsequent 
vegetation  based  upon  it,  even  on  a  solitary  island  in  the  midst  of  the 
Atlantic  ocean. 

The  conclusion  to  which  we  arrive  is,  that  animals,  vegetables,  and 
the  soil  hold  certain  properties  in  common,  alike  affecting  their  growth 
and  the  means  of  obtaining  nutriment.  When  circumstances  admit, 
they  all  appropriate  materials  but  little  if  at  all  removed  in  composition 
from  their  own  substance ;  but  they  also  are  enabled  to  generate  within 
their  system  more  or  less  compounds  suitable  to  their  immediate  wants 
from  the  same  elements  in  simpler  states  of  combination.  The  more 
capital,  therefore,  we  judiei^iiy  invest  in  organic  manures,  or  in  mineral 
manures  with  a  view  of  fostering  humus,  the  more  deeply  w«  plough 
and  pulverize  the  soil  within  prudential  limits,  the  larger  interest  accrues, 
not  only  by  the  increased  weight  and  quality  of  produce  above  ground, 
but  also  below  the  surface. 

Mount  Hermon,  Washington  County,  March,  1850. 


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